Answer:
51 DVDs
Step-by-step explanation:
Let the number of DVDs and CDs sold be x each.
Initial
Number of DVDs= 86
Number of CDs= 52
After selling
Number of DVDs= 86 -x
Number of CDs= 52 -x
Given that there are 3 times as many DVDs than CDs left,
86 -x= 3(52 -x)
Expand:
86 -x= 156 -3x
Bring x terms to 1 side, constant to the other:
3x -x= 156 -86
Simplify:
2x= 70
Divide both sides by 2:
x= 35
Amount of DVDs left
= 86 -x
= 86 -35
= 51
