Question 299576
Translate the problem into a pair of linear equations in two variables. Solve the equations using either elimination or substitution. State your answer for the specified variable. 
A child's bank contains $2.24 in pennies and nickels. If the number of pennies is 40 less than 3 times the number of nickels, then how many pennies are in the bank?

Let x be the number of nickels and y the number of pennies. We have then:

1.) y = 3*x - 40

Since each nickle is worth .05 and each penny .01 we also have:

2.) .05*x + .01*y = 2.24 

Multiplying both sides by 100 we have:

5x + y = 224

From the above we have y = -5x + 224

We can substitute -5x + 224 for y in equation 1.) and solve for x.

Once we have the value of x we can find y = -5x + 224.