PEMDAS
When solving an equation we do them in reverse order
AS adding and subtracting
MD multiplication and division
E exponents
Basically we are trying to get the variable alone.
12=10-3x
subtract 10 from each side
then divide by -3 on each side
3/5 x -12 = 18
first add 12 to each side
then multiply by 5/3 to each side