Steve has a photograph exhibit. In it, there are 15 more photographs of non-sporting events than of sporting events. How many of each does he have?

Question

40% of all of his photographs are about sports.

Solve the word problem with an equation.

Introduce a variable expression for each unknown.

Answer 1

It seems like you do not have to find the exact numbers here, but rather right out equations and simplify them as much as possible. 

 

Make x=the number of sport photographs and y=the number of non sport photographs. Make z=total number of photographs. Thus, x+y=z. 

You also know that .40z=x because 40% of the total (z) is the number of sports photographs. 

You also know that there are 15 more non sport photographs (y) than sport photos (x) so y=15+x. 

You now have equations for each unknown. You could substitute in the equations to represent the variables in different forms, but it is probably not necessary.