# Thread: Don't understand this problem.

1. ## Don't understand this problem.

I do kinda of, but for someone reason I doubt I'm getting the answer.

A cashier has $645 in 10 dollar and 5 dollar bills. There are 90 bills in all. How many of each does the cashier have? 10x + 5x = 645 15x=645 645-90=555 I know , I know this. but for some reason I can'tfigure it out. lol This is just 2 point for extra credit. got the other 14 questions right. Only had to do 8 of 15. Thanks 2. A cashier has$645 in 10 dollar and 5 dollar bills. There are 90 bills in all. How many of each does the cashier have?
let x = number of $10 bills y = number of$5 bills

A cashier has $645 in 10 dollar and 5 dollar bills. 10x + 5y = 645 There are 90 bills in all. x + y = 90 solve the system of equations using your favorite method. 3. Originally Posted by skeeter let x = number of$10 bills
y = number of $5 bills A cashier has$645 in 10 dollar and 5 dollar bills.

10x + 5y = 645

There are 90 bills in all.

x + y = 90

solve the system of equations using your favorite method.
let x be the amount of 10 dollar bills
let y be the amount of 5 dollar bills

(x+y=90)-5
10x+5y=645
-5x-5y=-450
5x=195
x=39

sub into original

39+y=90
y=90-39
y=51

therefore there were 39 10 dollar bills and 51 5 dollar bills

4. sorry, I figured it out, once I did the x and y .. before I did it , I was doing x and x, soon as I did x and y I got it. Thank You. I was confusing myself.

This is way I set it up to figure it out.

10x + 5 (90-x) = 625

Then took 90-39 = 51