Does anyone know what a, b, and c are?

Lining up the trapezoids you need to notice that you have measurements for the LEFT side of both trapezoids. These measurements will be used to set up the ratio of small to large. 8/12 = 2/3 is the ratio of small trapezoid to large trapezoid.
To find a: 8/12 = 12/a; cross multiply; 8a = 144, divide both sides by 8; a = 18
To find b: 8/12 = b/6; cross multiply; 12b = 48, divide both sides by 12; b = 4
To find c: 8/12 =c/15; cross multiply; 12c =120, divide both sides by 12; c = 10

Instead of using 8/12 you could have used the reduced version, 2/3.

He was paid 23 dollars for each lawn

The answer would he -4,-2 because the points are just on the opposite side. since the x axis is +4 it's going to he -4 and since the y axis is -2 it stays there because whaen rotated it stays in the third quadrant