How do u solve q+d(-2.5q+94.5)=60 using systems of equations?

Question

• q+d=60
• .25q+.10d=9.45

 

 

Answer 1

q+d=60, so q=60-d and 0.25q+0.10d=0.25(60-d)+0.10d=9.45; 15-0.25d+0.10d=9.45; 15-9.45=(0.25-0.10)d.

0.15d=5.55, d=5.55/0.15=37, so q=60-37=23. This looks q quarters plus d dimes = 60 coins, their combined value is $9.45. So the solution is 23 quarters ($5.75) plus 37 dimes ($3.70) = $9.45.