Find the value of if and .
Worker A can make a trinket in 4 hours, Worker B can make a trinket in 2 hours. When they work together, how long will it take them to make a trinket?
3 hours
1 $\frac{1}{3}$ hours
$\frac{1}{2}$ hour
1 $\frac{1}{2}$ hours
6 hours
if 
and 
.