Sally gave her brother 3.95 in quarters and dimes. if the number of quarters is 6 more then the number of dimes, how many quarters did sally give her brother

Let q be the number of 25 cent coins.

Let d be the number of 10 cent coins.

0.25q+0.10d = 3.95 ... (1)

q-d=6 ... (2)

(2) - > q-d = 6

q-d+d = 6+d

q = 6+d ... (2a)

(2a) - > (1) 0.25q+0.10d=3.95

0.25 (6+d) = 0.10d = 3.95

1.95+0.25d+0.10d = 3.95

0.35d = 3.95-1.5

0.35d/0.35 = 2.45/0.35

d = 7 ... (3)

(3) - > (2) q-d = 6

q-7 = 6

q=6+7

q = 13

There are 13 quarters and 7 dimes.