Thread: System of equation

I'm stumped on this one problem...

Bob has $4.95 in quarters and dimes. He has 3 times as many dimes as quarters.

I don't get how to set this up.

x=quarters
3x=dimes
4.95=total

so you take the worth of the coins times the amount, add them together for the total.

3x(.10)+.25x=4.95
.30x+.25x=4.95
.55x=4.95
.55x/.55=4.95/.55
x=9 (quarters)
3x=27 (dimes)

check your answer:
9 quarters equals $2.25
27 dimes equals $2.70
add them together and you get $4.95

Thanks so much!