Question

Pleas help me and can you explain how you got it.

Answer 1

21

Explanation:

straight line = 180 degrees ( H,D,R)

180 = 7x - 3 + 2x - 6

180 = 7x + 2x - 3 - 6 (group the same type number together)

180 = 9x -9 (simplify the numbers)

189 = 9x (+9)

21 = x (divide by 9)