4 Men and 6 Boys can finish a piece of work in 20 days, while 3 men and 4 boys can finish it in 28 days. Find the time taken by one man alone and that by one by alone to finish tthat work?

13 days
  • 4
The equ is 4x plus 6y eql to 20; 3x plus 4y equl to 28. By eliminating x variable by using elimination method we get 2y eqlto -52. Which implies y eql to -26. On substituting y eql to -26 in equ 4x plus 6y eql to 20, we get: 4x -156 eql to 20. Which implies x equl to 44. There fore the time taken by one man alone is 44 and the time taken by one boy alone is -26.
  • 0
4x + 6y = 20  -----(1)
3x + 4y = 28 -----(2)

(1) x 3
(2) x 4

we get, 
12x + 18y = 60  ----- (3)
12x + 16y = 112  ----(4)

(4) - (3)

-2y = 52
y = -26

substitutuing y = - 26 in (3)
12x + 18(-26) = 60
12x - 468 = 60
12x = 528
x = 528/12 = 44
 
  • -3
let time taken by one man alone = x
and time taken by one boy alone = y

4x+ 6y = 20  -----(1)
3x + 4y = 28 -----(2)

(1) x 3
(2) x 4

we get, 
12x + 18y = 60  ----- (3)
12x + 16y = 112  ----(4)

(4) - (3)

-2y = 52
y = -26

substitutuing y = - 26 in (3)
12x + 18(-26) = 60
12x - 468 = 60
12x = 528
x = 528/12 = 44
 
  • -2
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