1. 4x+5x= 90, x=10 First angle is 40 deg., the second is 50 deg., 10% of 40 is 4, so the second angle has to decrease by 4 deg., which is 8% of 50 deg.

2. (x+y+z)/3=2*(y+z)/2; cancel 2 on the right, (x+y+z)/3=y+z, mult by 3 both sides: x+y+z=3y+3z, subtr. y and z from both sides: x=2y+2z. Ta-dah!!

3.Check three points: -3, 0, 2 for x, and see which y is smallest.( answer is x=o, y=24-the smallest one)