Question

problem 17: (first taught in lesson 18) find y. after you enter your answer press go. y =

Explanation:

Step1: Use vertical - angle property

$x=2x - 80$

Step2: Solve for x

$80=2x - x$, so $x = 80$.

Step3: Use angle - sum property

The right - angle is $90^{\circ}$. The sum of the angles on a straight line is $180^{\circ}$. So $x + 90+y=180$. Substitute $x = 80$ into the equation: $80+90 + y=180$.

Step4: Solve for y

$170+y=180$, then $y=180 - 170=10$.

Answer:

$y = 10$