ok so
n=number of nickes
d=number of dimes
d+n=36
worth
2.20=worth of nickles+worth of dimes
worth of nickles=number of nickes times 0.05=0.05n
worth of dimes=number of dimes times 0.10 so
2.2=0.05n+0.1d
so we have
n+d=36
2.2=0.05n+0.1d
multiply the second equaiton by -10
-22=-0.5n-1d
add to first equation
36+n+d
-22=-0.5n-d +
14=0.5n+0d
14=0.5n
divide both sides by 0.5
28=n
subsitute
n+d=36
28+d=36
subtract 28
d=8
28 nickles and 8 dimes
