Question 903285
x = number of problems



missed 9 problems


got x-9 problems correct



(# correct)/(# total) = percent correct


(x-9)/x = 0.6


x-9 = 0.6x


-9 = 0.6x - x


-9 = -0.4x


-0.4x = -9


x = -9/(-0.4)


x = 22.5


Round up to get 23. So there are 23 problems total (23-9 = 14 are correct)