Question

In the diagram below, find the value of y.

Answer 1

y=130

Explanation:

1) combine all like terms for the inside angles of the triangle

• (3x-19) + (4x+8) + (x+7)
• 3x-19+4x+8+x+7
• 8x-4

2) because the sum of all angles = 180 add that to the sum of all like terms

• 8x-4=180
• add 4 on both sides and divide both sides by 8
• this should be x=23

3) now you replace the x's with 23

• (3(23) -19)
• 69-19
• 50

4) now we know that (3x-19)=50

5) take 180 and subtract 50

• this is because y and (3x-19) creates a supplementary angle which also equals 180

6) 180-50=130