.05n + .10d = 4.85
n - 34 = d
Substitute the second equation into the first equation and solve for n.
.05n + .10(n - 34) = 4.85
.05n + .10n - 3.4 = 4.85
combine like terms
.15n - 3.4 = 4.85
add 3.4 to both sides
.15n = 8.25
divide both sides by .15
n = 55
d = n - 34
d = 55 - 34
d = 21
CHECK
21 * .1 = 2.10
55 * .05 = 2.75
2.10 + 2.75 = 4.85
21 dimes and 55 nickels