Start by adding 20 to both sides to isolate '7b'. This gives you 7b = 3b + 32.
Next, Subtract 3b from both sides in order to make it so that the variable, which is 'b' in this case, is on one side of the equation.
This gives you 4b = 32.
Now divide both sides by 4 to cancel out 4b (opposite of multiplication is division).
This brings you to the answer b = 8 (32 divided by 4 is 8).
Hope this helps.