The answer is 59049 hope this helps
Step-by-step explanation:
You multiply the two other sides by itself like 12x12=144 and do that for all the sides that you know then you add up all of the numbers you got from adding like 144 plus 64 equals 208 and then 208 is the hypotenuse.
Let x = the next score
If (81 + 89 + 90 + 83 + 77 + x) ÷ 6 = 82
⇒ 420 + x = (82 × 6)
⇒ x = 492 - 420
x = 72
Thus to get an 82 average he need to get 72 on his next test.