How to write equivalent expressions by combining like terms

1.) 3a+5a put the a’s with the expression
3x2+5x2 The a=2 so combine them
6+10=4

2.)8x5-4x5
40-20=20

3.)5x-3+4x-3+-3
-15+-12+-3=-30
I just did 3 comment if u need more help. All you do is match it with the letter and combine them all.

Answer d; a supplementary angle = 180°, so if that angle = 150°, y would = 30°.