For example, if the straight line ∨ lies between m∨ and n, < Acb=60 degrees, and the angle between bc and straight line n is 25 degrees, then < A= how many degrees?
∫m∑n, the angle between the side BC and the straight line n is 25,
∴∠BCD=25。
∫△ABC is an equilateral triangle,
∴∠ACB=60，
∴∠ACD=60 -25 =35。
∫l∨m，
∴∠α=∠ACD=35。
So the answer is: 35.