A can do 1 job in 10 min. means 1/10 job per min.
B can do 1/15 job per min.
together A&B can do 1/10+1/15 =1/6 job per min.
1/6 job they spend 1 min
1 spend 1x1/(1/6) = 6 min
"Two significant figures" means that a digit after the second one could actually be anything ... it wasn't measured. 'X' could be anything from 230 to 239. 'Y' could be anything from 400 to 409.
The greatest possible value of that fraction is. (239)/(409 squared) .
45-15= 30-28= 2+18=20
Is that what the question was asking??
Answer:
The second graph represent the compound inequality
They would be negative nine and a positive ten:-9, 10
