Since 4 is right outside the (5 - x), you need to distribute the 4. so, you do 4 • 5 (20) and 4 • -x (-4x) which ends up as 20 -4x = 32.
then you solve! you subtract the 20 on the left side so you are only left with the -4x. since you subtracted the 20 in the left side, you have to do the same in the right. so, 32-20 is 12.
then, you are left with -4x = 12. to get the variable, x, alone, you have to divide it by -4. but, if you do this in the left, you HAVE to do it on the right too!