Call the number of hours that Isaac worked x.
Ruby worked x+6, because she worked 6 hours more than Isaac.
Svetlana worked 4(x+6), because she worked 4 times as many hours as Ruby.
All together, Isaac, Ruby, and Svetlana worked 126 hours.
You can add all of the amounts that they worked together in an equation to find how much is x:
x+x+6+4(x+6)=126
Distribute.
x+x+6+4x+24=126
Combine like terms.
6x+30=126
Subtract 30 from both sides.
6x=96
Divide both sides by 6.
x=16
Isaac worked 16 hours. Now, you can plug 16 in for x to find how much Ruby and Svetlana worked.
Ruby worked x+6 hours=16+6 hours=22 hours.
Svetlana worked 4(x+6) hours=4(16+6)=64+24 hours=88 hours
You can add all of their times together to make sure it equals 126 hours:
16+22+88=126
Isaac worked 16 hours; Ruby worked 22 hours; Svetlana worked 88 hours.
I hope this helps :)
