Benjamin has $6.90 in quarters and dimes. He has a total of 36 coins. How many quarters and dimes does he have?

Benjamin has $6.90 in quarters and dimes. He has a total of 36 coins. How many quarters and dimes does he have?

Let the number of quarters = Q

Let the number of dimes = D

Q+D = 36

.25Q + .10D =6.90, solve for Q, D

Q = 22 quartes

D = 14 dimes

Benjamin has $6.90 in quarters and dimes. He has a total of 36 coins. How many quarters and dimes does he have?

Let N be the number of quarters.....so......36 - N  is the number of dimes

And the total number of quarters times the value of each plus the number of dimes times the value of each = the total amount.....mathematically, we have

.25N + .10(36 -N)  = 6.90   simplify

.25N + 3.6 - .10N   = 6.90

.15N  + 3.6  = 6.90  subtract 3.6 from both sides

.15N  = 3.30    divide both sides by .15

N  = 22....this is the number of quarters

And 36 - N  = 36 - 22   =  14  is the number of dimes