Question 657502
If x=John's age, Sarah's age is 4x+3

If the difference is 33:

(4x+3)-x=33
4x-x+3=33
3x+3=33
3x+3-3=33-3
3x+0=30
3x=30
3x/3=30/3
x=10

If John's age is x, it is 10.
If Sarah's is 4x+3, it is 43.

Is the difference 33? YES!