Let the girl's age be g. Let the boy's age be b. We're given two equations:

- g = b + 3 (
*Older means we add)* - b + g = 35

b + b + 3 = 35

To solve for b, we type this equation into our search engine and we get:

b =

**16**

Now, to solve for g, we plug in b = 16 that we just solved for into equation (1):

g = 16 + 3

g =

**19**