X can copy 80 pages in 20 hours, x and y together can copy 135 pages in 27 hours. Then y can copy 20 pages in ?
A. 20 hours
B. 24 hours
C. 3 hours
D. 12 hours
Answer: Option A
Solution(By Examveda Team)
$$\eqalign{ & \Rightarrow {{\text{R}}_{\text{x}}} \cr & = \frac{{80}}{{20}} \cr & {\text{ = 4 pages/hour}} \cr & \Rightarrow {{\text{R}}_{{\text{x + y}}}} \cr & = \frac{{135}}{{27}} \cr & {\text{ = 5 pages/hour}} \cr & \Rightarrow {{\text{R}}_{\text{y}}} \cr & = {{\text{R}}_{{\text{x + y}}}} - {{\text{R}}_{\text{x}}} \cr & = 5 - 4 \cr & = 1{\text{ pages/hour}} \cr & \therefore {\text{y can copy 20 pages in}} \cr & = \frac{{{\text{20p}}}}{{{\text{1p/h}}}} \cr & = {\text{ }}20{\text{ hours}} \cr} $$Related Questions on Time and Work
A. 18 days
B. 24 days
C. 30 days
D. 40 days
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