Question

Mrs. Chans math class contributed 2 dollars and $1 coins to an earthquake relief fund. the number of $1 coins contributed was 8 less than 5 times the number of $2 coins contributed. if class raised total of 160 bucks, how many coins of each type was collected?

it says i have to solve this by the elimination method, and i cant seem to figure out.

Answer 1

Let x = number of $1 coins and y = number of $2 coins.

x = 5y - 8
x - 5y = -8

x + 2y = 160

Multiply first equation by 2 and second by 5.

2x - 10y = -16
5x + 10y = 800

Add the two equations.

7x = 784
x = ?

Put value of x in first equation to find y. To check, put both values into the second equation.