Luis has $10.25 in change in his piggy bank. The number of nickles is three times the number of dimes. The number of quaters is 1 more than four times the number of dimes. How many of each kind of coin does he have.
So 10.25=0.05n+0.1d+0.25q
n=3d
q=4*d+1
Substitute d and q to the top equation
So 10.25=0.05(3d)+0.1d+0.25(4*d+1)
Distribute 10.25=0.15d+0.1d+1d+0.25
Simplify 10.25=1.25d+0.25
10.25-0.25=1.25d --> 10/1.25=d--> d=8
plug 8 back into the equations
3*8=n --> n=24
4*8+1=q --> q=33
If you replace all the variables with the numbers, you should get 10.25