(20 + 12) - 8, since the question states n is EIGHT less than the sum of 20 and 12.

The equation of a elipse:

The length of the major axis is equal 2a if a > b or 2b if b > a.
We have

therefore the length of the major axis is equal 2 · 7 = 14.
You would divide 198 by 9.
198÷9=22
Each person would clean 22 rooms.
a. If we subtract 75 from 550 twice, we get 400, which is the third member to join. Subtract 75 from 400, we get $325, the fourth member to join.
b. It is not possible that a member would join for free if it was a large family. 75 does not fit into 550 evenly. You can prove this by solving the expression 550÷75.
c. The lowest amount that a member would pay to join is $25.00. It would be the 7th member.