Bobosharif S. answered • 03/30/18

Tutor

New to Wyzant
PhD in Math, MS's in Calulus

Let x, y, z denote the amount Billy, Derek and Jasob have. Then

x+y+z=680

x=(3/4)y

y=(7/9)z

If you solve this system of equations, you have to obtain:

x=168, y=224, z=288.

You can solve by substitution, for example. By using the second and the second equations from the first one you get

(3/4)y+y+(9/7)y= 680.

y=224.

Then you find x and z.