Answer:
87 points
Step-by-step explanation:
lets take "x" as the avg test scores of the past 6 tests
so
since their are 6 tests, we would represent the 6 tests as "6x"
to find average we need to add all numbers, and divide by the number of numbers
so since the final exam counts as two tests we need to add "99" twice
so
(6x+99+99)/8=90
multiply by "8" on bots sides and add 99 and 99 together
6x+198=720
subtract 198
6x=522
divide by 6
x=87
hope this helps