Question 987099
.
D=dimes; Q=quarters=D+6
.
$0.10D+$0.25Q=$5.70
$0.10D+$0.25(D+6)=$5.70
$0.10D+$0.25D+$1.50=$5.70
$0.35D=$4.20
D=12 There are 12 dimes.
Q=D+6=12+6=18 
ANSWER: There are 18 quarters.
.
CHECK:
.
$0.10D+$0.25Q=$5.70
$0.10(12)+$0.25(18)=$5.70 
$1.20+$4.50=$5.70
$5.70=$5.70