So average is of the first 6 tests is 82 well that means
(test1 + test2+ test3+ test4 + test5+test6)/6 = 82
so now let do some cross multiplliying
test1 + test2 + test3 + test 4 + test5 +test6 = 82*6
test1 + test2 + test3 + test 4 + test5 +test6 = 492
now lets see if we can find that 7th test score
(test1 + test2 + test3 + test4 + test5 +test6 + test7)/7 = 80.5
So look we found test1 + test2 + test3 + test4 + test5 +test6 to be 492 so lets substitute.
(492 + test7 )/7 = 80.5
test7 = (80.5*7)-492 = 71.5
The rejection region is give by

where the test statistics is given by

i.e.

Thus,

Using the statistical table, the level of the test is 0.04.
By using the picture that was provided below, you can see that
m<MXN is greater than m<YZX.
Angles m<LZX is equal to m<ZYX + m<YZX and
m<MYL is equal to 180 degrees minus M<ZYX.
I hope this helps! Have a good day