Let's solve each problem step by step. The goal is to
create equivalent ratios by finding the missing number that makes the two ratios equal.
We use the idea that:
> If $ a:b = c:d $, then $ \frac{a}{b} = \frac{c}{d} $, and we can cross-multiply or scale up/down proportionally.
---
(1) $ 8:3 = \_\_ : 27 $
We want to find what number $ x $ makes $ 8:3 = x:27 $.
Since $ 3 \times 9 = 27 $, multiply both parts of the ratio $ 8:3 $ by 9:
$$
8 \times 9 = 72,\quad 3 \times 9 = 27
\Rightarrow 72:27
$$
✔ Answer:
72
---
(2) $ 15 : \_\_ = 24 : 56 $
Simplify $ 24:56 $: divide both by 8 → $ 3:7 $.
So $ 15:x = 3:7 $.
Now, $ 15 \div 3 = 5 $, so multiply $ 3:7 $ by 5 → $ 15:35 $
✔ Answer:
35
---
(3) $ 8:24 = 1:\_\_ $
Simplify $ 8:24 $: divide both by 8 → $ 1:3 $
✔ Answer:
3
---
(4) $ 12 : \_\_ = 16 : 24 $
Simplify $ 16:24 $: divide by 8 → $ 2:3 $
So $ 12:x = 2:3 $
Now, $ 12 \div 2 = 6 $, so multiply $ 2:3 $ by 6 → $ 12:18 $
✔ Answer:
18
---
(5) $ 7:56 = \_\_:72 $
Simplify $ 7:56 $: divide by 7 → $ 1:8 $
Now find $ x $ such that $ x:72 = 1:8 $
So $ x = 72 \div 8 = 9 $
✔ Answer:
9
---
(6) $ \_\_:20 = 8:5 $
We have $ x:20 = 8:5 $
Cross-multiply: $ 5x = 8 \times 20 = 160 $ → $ x = 160 \div 5 = 32 $
✔ Answer:
32
---
(7) $ 40:25 = 8:\_\_ $
Simplify $ 40:25 $: divide by 5 → $ 8:5 $
So $ 8:5 $ → answer is
5
✔ Answer:
5
---
(8) $ 5 : \_\_ = 1:7 $
We know $ 5:x = 1:7 $
$ 5 \div 1 = 5 $, so multiply $ 1:7 $ by 5 → $ 5:35 $
✔ Answer:
35
---
(9) $ 12:5 = 72:\_\_ $
$ 12 \times 6 = 72 $, so multiply both sides of $ 12:5 $ by 6 → $ 72:30 $
✔ Answer:
30
---
(10) $ 8 : \_\_ = 1:9 $
$ 8:x = 1:9 $
$ 8 \div 1 = 8 $, so multiply $ 1:9 $ by 8 → $ 8:72 $
✔ Answer:
72
---
(11) $ 20:28 = 5:\_\_ $
Simplify $ 20:28 $: divide by 4 → $ 5:7 $
✔ Answer:
7
---
(12) $ 99 : \_\_ = 11:7 $
We have $ 99:x = 11:7 $
Divide 99 by 11 → $ 99 \div 11 = 9 $, so multiply $ 11:7 $ by 9 → $ 99:63 $
✔ Answer:
63
---
(13) $ 27:72 = 3:\_\_ $
Simplify $ 27:72 $: divide by 9 → $ 3:8 $
✔ Answer:
8
---
(14) $ 9:2 = \_\_:18 $
We want $ x:18 = 9:2 $
$ 18 \div 2 = 9 $, so multiply $ 9:2 $ by 9 → $ 81:18 $
✔ Answer:
81
---
(15) $ 12:7 = \_\_:56 $
$ 56 \div 7 = 8 $, so multiply $ 12:7 $ by 8 → $ 96:56 $
✔ Answer:
96
---
(16) $ 5:35 = 1:\_\_ $
Simplify $ 5:35 $ → divide by 5 → $ 1:7 $
✔ Answer:
7
---
(17) $ 55:25 = \_\_:5 $
Simplify $ 55:25 $: divide by 5 → $ 11:5 $
So $ 11:5 $ → answer is
11
✔ Answer:
11
---
(18) $ 5:10 = 25:\_\_ $
Simplify $ 5:10 $ → $ 1:2 $
Now $ 25:x = 1:2 $
Multiply $ 1:2 $ by 25 → $ 25:50 $
✔ Answer:
50
---
(19) $ 48:28 = 12:\_\_ $
Simplify $ 48:28 $: divide by 4 → $ 12:7 $
✔ Answer:
7
---
(20) $ \_\_:27 = 8:9 $
We have $ x:27 = 8:9 $
$ 27 \div 9 = 3 $, so multiply $ 8:9 $ by 3 → $ 24:27 $
✔ Answer:
24
---
✔ Final Answers:
| Problem | Answer |
|--------|--------|
| (1) | 72 |
| (2) | 35 |
| (3) | 3 |
| (4) | 18 |
| (5) | 9 |
| (6) | 32 |
| (7) | 5 |
| (8) | 35 |
| (9) | 30 |
| (10) | 72 |
| (11) | 7 |
| (12) | 63 |
| (13) | 8 |
| (14) | 81 |
| (15) | 96 |
| (16) | 7 |
| (17) | 11 |
| (18) | 50 |
| (19) | 7 |
| (20) | 24 |
Let me know if you'd like this as a printable sheet or with explanations for each!
Parent Tip: Review the logic above to help your child master the concept of ratio and proportion worksheet with answers.