Hey!
The sum of all 3 angles in a triangle always adds up to 180°. One of the angles is 70°. Another angle is 80° because 180 - 100 = 80. Add the 2 angles and subtract it from 180.
[tex] 70 + 80 = 150 [/tex]
The sum of the 2 angles is 150°. Subtract that from 180
[tex] 180 - 150 = 30 [/tex]
That means x is equal to 30
[tex] \framebox{Answer = 30 \° = B} [/tex].
