Answer: The percent gain was 25%.
Step-by-step explanation:
Given, Cost price of lot = $1,200
Selling price of lot = $1,500
The percent gain = 
⇒ Percent gain =

Hence, the percent gain was 25% based on his purchase.
b...............................................................................
Since you know the given angle is 46deg. You also know that a straight line is equal to 180deg. So it's a supplementary angle, therefore you subtract 46 from 180 and get 134. And since the l, m, and n are parallel, they have congruent angles. So x = 134deg.