Question

Adam's average homework score, worth 40% of his grade, is 76%.
His average unit test score, worth another 40%, was 81%. The
final makes up the rest of his total grade. What is the minimum
number of questions he need to answer correctly on the 50-question
final exam to earn a B (80%) in the class?

a. 45
b. 40
c. 43
d. 42

Can someone help me solve this problem