Suppose that three lines have same y-intercept and that their slopes are 1/3 , 1/5 , 1/7. If the sum of x-intercept of the lines is 1000m, then heir common y-intercept , is equal to

(A) 200/3

(B) 3/200

(C) -3/200

(D) -200/3

let y cordinates oaf all the lines be b ;

 then equations of 3 lines are 

 x/a+y/b=1

x/c+y/b=1

x/d+y/b=1;

from finding slopes we get

a/b=-3,

c/b=-5,

d/b=-8,

[a+b+c]/b=-15

b=-1000/15=-200/3

so the answer is -200/3 (d)

 for more details email me at ananth.c.jayan@gmail.com