work & time

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if the ratio of work done by (x-1) men in (x+1)days to the work done by (x+2)men in (x-1)days is 9:10, then x is equal to
A. 5
B. 6
C. 7
D. 8

[amising6]

if the ratio of work done by (x-1) men in (x+1)days to the work done by (x+2)men in (x-1)days is 9:10, then x is equal to
A. 5
B. 6
C. 7
D. 8

man work in 1st case=(x-1)(x+1)
man work in 2nd case=(x+2)(x-1)
(x-1)(x+1)/(x+2)(x-1)=9/10
x+1/x+2=9/10
10x+10=9x+18
x=8