Question 100223
sam can do 1/7 of the job in 1 hr.
sis +sam can do 1/4.5 of the job in 1 hr.
let 1/x=what part of the job sis can do in 1 hr
1/7+1/x=1/4.5
multiply 63 times both sides: 9x+63=14x
subtract 9x from both sides: 5x=63
x=63/5=12.6 hrs it takes her to stuff 1150 shrimp BUT she only has to stuff 1/2 that much (575) so the answer is 6.3 hrs.
Ed