Question 483649
Let they will work together x hours
In 1 hour Sarah can do {{{1/9}}} part of job, in x hours she will do {{{x/9}}}part of job
In 1 hour Floyd  can do {{{1/15}}} part of job, in x hours he will do {{{x/15}}} part of job
Together in x hours they will finish all job
The equation
{{{x/9+x/15=1}}} multiply by 45
{{{5x+3x=45}}}
{{{8x=45}}}
{{{x=45/8}}}=5{{{5/8}}} 
in 5{{{5/8}}} hours they will clean an attic together