Math Help - System of equation

1. 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. 2. 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

3. Thanks so much!