Which subtraction expression does the number line model show?

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

In trapezoid abcd, ac is a diagonal and ∠abc≅∠acd. find ac if the lengths of the bases bc and ad are 12m and 27m respectively.

Why can't my rank go i have 1723 points, but my rank is only at ambitious, which is only 250 points! like, (p. s. i know this isn't related to math, but i just don't know why it's doing this and i would really appreciate if someone could tell me whats going on with this)