Help on math edmentum! Please.

1. what are the missing reasons in the proof 2. it's in the second picture and 3

Frank owns a $141,000 home, for which he has a 30-year mortgage in the amount of $700 a month. once he has paid off mortgage, how much will he have paid in investment? a. $111,000 b. $109,000 c. $120,000 d. $141,000

What is the slope of the line (-7,2) (4,6)