You would use order of operations: PEMDAS
P(parenthesis) E(exponents) MD(multiplication/division) AS(addition/subtraction)
with MD and AS order doesnt matter.
8(5-32) you would start with inside the Parenthesis for "P" so (5-32)=(-27)
next you would go to the E but because you dont have an exponent you go to the next step with is the "MD" you have multiplication so next would be 8(-27) and 8 multiplied by -27 is: 8(-27)= -216
ANSWER: -216
The mean of n numbers is the sum of the numbers divided by n.
You have a mean score of 84 after taking 5 tests. Let x be the sum of scores.

You scored a total of 420 points on five tests.
You need to have a mean score of 85 after taking 6 tests. Let y be the score you need to obtain. Your total score on 6 tests is 420+y.

You need to score 90 points on the sixth test.