what you do to oneside of an eqution (=) you must do to the other side.
we will now try to get the unknown (x) by itself on one side of the equation (=)
by multiplying both sides by 7 (the denominator of x/7).
5/8 = x/7
which gives us 7 times 5/8 = 7 times X/7 which gives us
35/8 = 7x/7 which becomes 4 3/8 = x