Answer:
let the opposite angle of 60° be x.
60°+ 80°+x=180°(by angle sum property)
140°+x=180°
x=180°-140°
x=40°
let the opposite angle of 65° be y
so, 40°,100°and y lie on a straight line so there sum is equal to the 180°
40°+100°+y=180°
140°+y=180°
y=180°-140°
y=40°
now 65°,y and ? are triangle so, there sum is equal to the 180°.
y+65°+?=180°
40°+65°+?=180°
105°+?=180°
?=180°-105°
?=75°