Question 334338
Add their rates of doing dishes
Call the "dishes" 1 job
For Jimmy:
{{{1/20}}} is his rate (1 dishwashing job/20 min)
For Susie:
{{{1/15}}} is her rate (1 dishwashing job/15 min)
Working together:
{{{1/20 + 1/15 = 1/x}}} (1/x is 1 dishwashing job/x min)
Now solve for {{{x}}}
Multiply both sides of the equation by {{{30x}}}
{{{3x + 2x = 30}}}
{{{5x = 30}}}
{{{x = 6}}}
Working together, they can do the dishes in 6 min