40+60+y=180
y=180-100
y=80
A triangle is 180° so you add all the numbers available in the trianle and minus it with 180 to see what is left from the 180 and that will be the inner angle answer
X=180-80=100
A straight line is also 180° so if u minused one side which in our case is 80 u will get the rest which is the outer angle
