Question

I have a total of 20 coins
they are all dimes and quarters that total $11.50
how many of each coin do I have?
x=#dimes
y=#quarters
if you have 20 coins then
x+y=20
and if the amount of money totals (money per coin)x(# that coin) then
0.1x+0.25y=11.50

you then have two equations
x+y=20
0.1x+0.25y=11.50

you can use these two eqns to solve for the number of each coin, x an y