Need some help with this math problem?

Question

A basketball player made 12 out of 15 throws he attempted. He wants to know how many consecutive free throws he would have to make to raise the percent of successful free throws to 85%.

Write an equation to represent this situation, then solve it. How many consecutive free throws would he have to make to raise his percent to 85%?

Answer 1

The basketball player is currently at 12/15 = 0.80 = 80%

 

To get to 85% over the next x throws, assuming they are no misses:

 

(12 + x) / (15 + x) = 85/100

100(12+x) = 85(15 + x)

1200 + 100x = 1275 + 85x

  15x = 75

      x = 75/15 = 5

----

Ans: the player would have to make 5 consecutive free throws to raise the percentage to 85%

----

check:   (12+5) / (15+5) = 17/20 = 0.85 = 85%