Question 982560
First goal is find their actual rates.


Let x be the time for Joseph to paint one whole room.
2x is then time for Sandra to paint one whole room.


PERSON ______________RATE
Sandra______________{{{1/(2x)}}}
Joseph______________{{{1/x}}}


What Joseph can do:
45 minutes is {{{3/4}}} hour.
{{{(1/x)*(3/4)=1/4}}}------<i>Joseph takes 45 minutes to paint one quarter of a room.</i>
Now you can find Joseph's rate and Sandra's rate.


{{{x(4/3)=4}}}
{{{x=4(3/4)}}}
{{{x=4}}}-------Time in hours for Joseph to paint one room
meaning his rate is  {{{1/4}}} Rooms per Hour.


Sandra's rate is then  {{{1/8}}} rooms per hour.


Do the rest!