Ok... I'm not going to give you answers but I'll help you.
Examples:
Example 1:
2-4(3x+5) --- distribute the -4 to the 3x+5 to get...
2-12x-45 ---- do 2-45
-43-12x
and that's your answer since you can't combine the -43 with the -12x cuz, the -43 does have a variable.
Example 2:
5y+4-2y ---- so simplify first. 5y-2y. to get...
3y+4
and that the answer
cuz you can't combine a number with a variable(letter. y, x, etc.) with one that doesn't.
I hope this helps. This is easy. Trust me. if you still don't get it. Just comment. Hope this helps! :)