Question

What is the value of x?

Answer 1

we know that

An exterior angle is equal to the sum of the two non adjacent angles

so

In this problem

$100\°=x\°+70\°$

Solve for x

Subtract  $70\°$ both sides

$x\°+70\°-70\°=100\°-70\°$

$x\°=30\°$

therefore

the answer is the option D

$30\°$

Answer 2

An exterior angle is equal to the sum of the 2 non adjacent angles. In this case

100 = x + 70 Subtract 70
x = 100 - 70
x = 30