" 7b ÷ 12 " can be written as " 7b / 12 ". That makes the problem easier,
because we know a lot of things that we can do with fractions.
7b / 12 = 4.2
Multiply each side of the equation by 12:
7b = (4.2 x 12) = 50.4
Divide each side of the equation by 7 :
b = 50.4 / 7 = 7.2
