Find the number of each kind of object in the collection

Question

Curt has 12 models in all. Three of the models are airplanes. Curt has 5 more models of cars than boats. How many models of cars does Curt have?

Answer 1

a + c + b =12

3 = a

b + 5 = c

Substitute into the original equation:

3 + b + 5 + b = 12

Solve for b to find the number of boats.

Add 5 to the number of boats to find the number of cars.