Question 1008205
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{{{1/3}}} + {{{1/5}}} = {{{5/15 + 3/15}}} = {{{8/15}}}.


It will take {{{15/8}}} hour for Bob and Barbara to paint the room working together.


For details see the lesson <A HREF=http://www.algebra.com/algebra/homework/Rate-of-work-word-problems/Word-problems-WORKING-TOGETHER-by-Fractions.lesson>Using fractions to solve word problems on joint work</A> in this site, 

where you will find a bunch of typical solved problems on joint work.