Question

[PLEASE HELP! + 15 POINTS] Wendy's sister said she would pay Wendy a quarter for every correct answer but Wendy would have to pay a dime for every incorrect answer. If Wendy made $3.80 after 25 problems, how many problems did she get correct?

Answer 1

She got 18 correct

How to do this:

25 x 25 = 6.25 if she got it correct

20 x 25 = 5.00 - 10 - 10 -10 -10 -10 = 4.50

18 x 25 = 4.50 - 10 -10 -10 -10 -10 -10-10 = 3.80