posted by TJ on .
Find the number of each kind of object in the collection
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?
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.