isolate the variable. this is done by putting only the variable on the left side and the numbers on the right side. when moving the 5 to the right side, it is counted as a -5 because of the minus in front. when moving it, be sure to change from - to + and vice versa.
4x = 16 + 5
4x = 21
x = 21/4
x = 5.25
b:
same process
35 + 3x - 11 = 23
move the 35 to the right, changing it to a -35
3x - 11 = 23 - 35
move the -11
3x = 23 - 35 + 11
3x = -12 + 11
3x = -1
x = -1/3
x = -0.33
Hope I could help! If you have any trouble, tell me in the comments.