Write and solve an equation

Question

One month, Ruby worked 6 hrs more than Isaac, and Svetlana worked 4 times as many hrs as Ruby. Together they worked 126 hrs. Find the number of hrs each person worked 

Answer 1

Let Isaac's hours be x, Ruby's be y, and Svetlana's be z.  Then x+y+z=126.

 

     y=x+6

     z=4y=4(x+6)

 

Then x+y+z=126 is transformed to x+(x+6)+4(x+6)=126

     6x+30=126

     6x=96

     x=16

 

     y=x+6=22

 

     z=4y=88