Ed earned $112 for 8 hours of work. At this rate, how much will he earn of 40 hours of work?

Ed earned $112 for 8 hours of work. At this rate, how much will he earn for 40 hours of work?

(1) One way to solve this is to find the unit rate. $112 in 8 hours reduces to $14 per one hour work. (Take 112/8 and simplify if necessary.) Thus Ed earns $14 for every hour worked -- working 40 hours yields 14*40=$560

Note that the units work: $/hrs*hrs gives dollars as the unit.

(2) An alternative is to set up a proportion: $112/8hrs=$x/40hrs

Multiply both sides by 40hrs to get (112)(40)/8=560 and the hours units cancel leaving dollars as the units.