Which is a perfect square between 49 and 121? a. 36 b. 50 c. 99 d. 100

36 and 100 are both square numbers.
However, only 100 is within the given range.

7x - 81 = -2 + 72.
First you add up the left side. This gives us:
-2 + 72 = 70
So the equation becomes:
7× - 81 = 70
Now we add up 81 on both sides to get rid of the 81 on the left
7x = 151
Now divide both sides by 7
x = 151/7

I hope this clears it up for you! :)