A student missed 15 problems on a mathematics test and received a grade of 80%. If all the problems were of equal value, how many problems were on the test?

75 problems

Step-by-step explanation:

Let x be the number of problems on the test and x-15 be the number of correct answers the student got on the test:

(x-15)/x = 0.80

x-15 = 0.80x

-15 = -0.20x

75 = x

Therefore, there were 75 problems on the test

the answer will be b x² +x-1

step-by-step explanation: