If we consider that #x# is Edward's age, twice of his age is #2x# and 3 more than that, #2x+3#, is equal to his mom's age. so we can form an algebraic equation as follows.

#2x+3 = 57#

We should take #+3# to the other side of the equation

#2x+3 -3 =57-3#

#2x = 54#

Isolate #x#: take #2# to the other side of the equation