Can someone help me please i will give you brainiest

18. 1x+15
19. 15
20. 1x
21. distributive property is when you multiply a number by the numbers inside of the parenthesis. for example 3(x+2) you would multiply 3 times x to get 3x and 3 times 2 to get 6. the equation would be 3x+6.
(i hope this helps also sorry if i get some of the answers wrong)

18. 3(-x+5)+4x
-3x+15+4x
=x+15
19. 2x+7-2(x-4)
2x+7-2x-8
=1
20. 3x-2(x+3)+6
3x-2x+6+6
=x+12
21. The distributive property is when you take the number before the parenthesis and multiply both numbers inside the parentheses by that number (this only works if you are multiplying the number if the number is divided, added, subtracted,etc. this process will not work)