Question

Marina is solving the equation below by using the multiplicative inverse, or the reciprocal.

One-fifth (x minus 2) = 20

By which number should Marina multiply both sides of the equation as the first step in solving it?
One-fifth
Four-fifths
5
20

Answer 1

5

Multiply both sides by the reciprocal of 1/5, which is 5: 5*(1/5)(x−2)=5*20 ⇒ x−2=100 (so x=102).