Thomas takes a break from his work every 20 minutes while elaine takes a break every 30 minutes. how often do they take a break at the same time assuming that they start work together?

Thomas and Elaine share a furtive meeting once every hour while
on their breaks.  Not much happens on these occasions, though. 
Thomas gets three breaks an hour, but Elaine only gets two, so
she's always too tired.

If they nenenenenenene

What am i doing here. add?