Sue can sew a precut dress in 3 hours. Helen can sew the same dress in 2 hours. If they work together, how long will it take them to complete sewing that dress? Give your answer rounded to one decimal point if necessary

together: 
1/3+1/2=1/t 
t=(3x2)/(3+2)=6/5 

1 hr 12 min 

:)