Solving System of Equations by Substitution - Math worksheet with problems and examples.

The image displays a worksheet titled "Solving System of Equations by Substitution" from Cuemath. It contains 8 problems, but the equations for questions 1-5 and the specific values for questions 7 and 8 are missing or obscured, making them unsolvable as presented.

Here is the analysis:

1. Questions 1-5: These require solving systems of linear equations using substitution. However, the actual equations are not visible or are represented by symbols like `=–`, `+ =`, etc., which do not constitute valid mathematical expressions. Without the correct equations, no solution can be provided.
2. Question 6: This asks about the number of solutions for a pair of equations, also represented by incomplete symbols (`– + =` and `– =–`). Without the actual equations, it's impossible to determine if they have a unique solution, no solution, or infinitely many solutions.
3. Question 7: This is a word problem about ages. The father's current age is stated to be eight times his son's age. After seven years, the father's age will be one less than four times his son's age. This problem *can* be solved.
4. Question 8: This is a word problem about angles in a triangle. The specific angle measures and relationships are missing (represented by blanks and symbols), making it unsolvable.

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Solution for Question 7:

Let the present age of the son be $x$ years.
Then, the present age of the father is $8x$ years.

After seven years:
* Son's age will be $x + 7$ years.
* Father's age will be $8x + 7$ years.

According to the problem, after seven years, the father's age will be one less than four times his son's age:
$8x + 7 = 4(x + 7) - 1$

Now, solve the equation:
$8x + 7 = 4x + 28 - 1$
$8x + 7 = 4x + 27$
Subtract $4x$ from both sides:
$4x + 7 = 27$
Subtract 7 from both sides:
$4x = 20$
Divide by 4:
$x = 5$

So, the son's present age is 5 years.
The father's present age is $8 \times 5 = 40$ years.

Answer for Question 7:
The present age of the father is 40 years, and the present age of the son is 5 years.

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Summary:

* Questions 1-6 and 8 cannot be solved due to missing or invalid information.
* Question 7 can be solved, yielding the father's age as 40 years and the son's age as 5 years.