Balance the Scales worksheet for practicing weight equivalence in grams and kilograms.

To balance the scales, the total weight on the left side must equal the total weight on the right side. We need to find the missing weights for each problem (a through j).

Important Conversion:
1 kilogram (kg) = 1000 grams (g).
We will convert everything to grams to make the math easier.

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Problem a:
* Left side: $300\text{ g} + 700\text{ g} = 1000\text{ g}$
* Right side: $1\text{ kg} = 1000\text{ g}$
* Check: $1000\text{ g} = 1000\text{ g}$. The scale is already balanced.
* Answer: The scale is balanced as is. (If a box implies a missing number to be filled, it might be 0, but usually these problems have a blank box for a missing weight. Looking closely at 'a', there are no empty boxes. It is an example or already solved. Let's look at the others which have empty white boxes.)

*Wait, looking at the image structure:*
- a: Left has 300g and 700g. Right has 1kg. No empty boxes. This is likely an example showing that $300+700=1000$, which equals 1kg.
- b: Left has 1kg. Right has 400g and an empty box.
- c: Left has 2kg. Right has 1200g and an empty box.
- d: Left has 2500g and an empty box. Right has 4kg.
- e: Left has 300g and an empty box. Right has 600g.
- f: Left has 1kg. Right has 250g and an empty box.
- g: Left has 2kg. Right has 1800g and an empty box.
- h: Left has 1kg and an empty box. Right has 1300g.
- i: Left has 330g, 670g, and an empty box. Right has 1100g.
- j: Left has an empty box. Right has 150g, 230g, and 270g.

Let's solve b through j.

Problem b:
* Left side: $1\text{ kg} = 1000\text{ g}$
* Right side: $400\text{ g} + \text{?}$
* Equation: $1000 = 400 + \text{?}$
* Calculation: $1000 - 400 = 600$
* Missing weight: 600 g

Problem c:
* Left side: $2\text{ kg} = 2000\text{ g}$
* Right side: $1200\text{ g} + \text{?}$
* Equation: $2000 = 1200 + \text{?}$
* Calculation: $2000 - 1200 = 800$
* Missing weight: 800 g

Problem d:
* Right side: $4\text{ kg} = 4000\text{ g}$
* Left side: $2500\text{ g} + \text{?}$
* Equation: $2500 + \text{?} = 4000$
* Calculation: $4000 - 2500 = 1500$
* Missing weight: 1500 g (or 1 kg 500 g)

Problem e:
* Right side: $600\text{ g}$
* Left side: $300\text{ g} + \text{?}$
* Equation: $300 + \text{?} = 600$
* Calculation: $600 - 300 = 300$
* Missing weight: 300 g

Problem f:
* Left side: $1\text{ kg} = 1000\text{ g}$
* Right side: $250\text{ g} + \text{?}$
* Equation: $1000 = 250 + \text{?}$
* Calculation: $1000 - 250 = 750$
* Missing weight: 750 g

Problem g:
* Left side: $2\text{ kg} = 2000\text{ g}$
* Right side: $1800\text{ g} + \text{?}$
* Equation: $2000 = 1800 + \text{?}$
* Calculation: $2000 - 1800 = 200$
* Missing weight: 200 g

Problem h:
* Right side: $1300\text{ g}$
* Left side: $1\text{ kg} + \text{?} = 1000\text{ g} + \text{?}$
* Equation: $1000 + \text{?} = 1300$
* Calculation: $1300 - 1000 = 300$
* Missing weight: 300 g

Problem i:
* Right side: $1100\text{ g}$
* Left side: $330\text{ g} + 670\text{ g} + \text{?}$
* First, add the known weights on the left: $330 + 670 = 1000\text{ g}$
* Equation: $1000 + \text{?} = 1100$
* Calculation: $1100 - 1000 = 100$
* Missing weight: 100 g

Problem j:
* Right side: $150\text{ g} + 230\text{ g} + 270\text{ g}$
* Add them up:
* $230 + 270 = 500$
* $500 + 150 = 650\text{ g}$
* Left side: Empty box ($\text{?}$)
* Equation: $\text{?} = 650$
* Missing weight: 650 g

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Final Answer:
Here are the values to fill in the boxes for each problem:

* b: 600 g
* c: 800 g
* d: 1500 g
* e: 300 g
* f: 7