Final answer:
Using the given information that Bob is 4 years older than Sue and their ages sum up to 42, we set up two equations. Solving these equations, Sue's age is discovered to be 19 years, and hence, Bob's age is found to be 23 years.
Step-by-step explanation:
To solve the problem which states that Bob is 4 years older than Sue and the sum of their ages is 42, we set up two equations based on the given information. Let's denote Sue's age as S and Bob's age as B. From the information, we can form the following two equations:
1. B = S + 4
2. B + S = 42
By substituting the first equation into the second, we get:
S + 4 + S = 42
This simplifies to:
2S + 4 = 42
Subtracting 4 from both sides gives us 2S = 38, so dividing both sides by 2 yields:
S = 19
Now that we know Sue's age, we can easily find Bob's age by adding 4 to it:
B = S + 4
B = 19 + 4
B = 23
Therefore, Bob is 23 years old.