Working simultaneously at their respective constant rates, machines a and b produce 800 nails in x hours. working alone at its constant rate, machine a produces 800 nails in y hours. in terms of x and y, how many hours does it take machine b, working alone at its constant rate, to produce 800 nails?
(a) x/(x+y)(b) y/(x+y)(c) xy/(x+y)(d) xy/(x-y)(e) xy/(y-x)

E.

Step-by-step explanation:

Given : Working simultaneously at their respective constant rates, Machines A and B produce 800 nails in x hours.

Taking whole job as 1.

The rate of Machines A and B working together =

Working alone at its constant rate, Machine A produces 800 nails in y hours.

The rate of work by Machines A =

Let t be the time taken by Machine B to complete the whole work .

The rate of  work by Machines B will be :-

Hence, the expression for hours taken by Machine B, working alone at its constant rate, to produce 800 nails :

1.4

2.3

step-by-step explanation:

the formula for the constant of variation is

y= kx

divide each side by x

y/x =kx/x

y/x =k

we know a and y

1.   y/x = k

4/1 =4

check the other values to make sure they are the same

8/2 = 4   12/3 =4   and 16/4 =4  

the constant of variation is 4

2.   y/x = k

3/1 =3

check the other values to make sure they are the same

6/2 = 3   9/3 =3   and 12/4 =3  

the constant of variation is 3