+69 The first step is to add all the like terms on each side. once you get that done you can move the like numbers to the other side in which it belongs. To put it simply, this is like finding a missing number, you should once you find an answer get the same number on both sides.
remember when doing this, negative numbers when moved become positive so add that to the other side.
example
3r+42=36+4r
1)look for like terms
2)subtract 3r to the other side of equal sign-> 3r+ 42=36+4r-3r
3) do the same steps for 36. you should end up with 6=r
4) plug the answer into the original equation.
8x + ( 16-25) = 7x - 21 + 3x
8x - 9 = 10x - 21
- 9 + 21 = 10x - 8x
12 = 2x
x = 6
