Answer:
x=21.25
Explanation:
The lower two angles will be equal in an isosceles triangle and all angles in a triangle add up to 180 degrees so:
75+(2x+10)+(2x+10)=180
75+4x+20=180
4x=85
x=21.25
(both lower angles=52.5 degrees)
Proof:
52.5+52.5+75=180