#### Answer

It took 1.25 hours to install the DVD system.

#### Work Step by Step

Let X represent the number of hours it took to install the DVD system.
60 dollars an hour for installation means 60X
An additional 379 dollars for the DVD player makes the expression 379 + 60X
Robin paid a 454 bill for a car DVD system.
So, we obtain: 379 + 60X = 454
Subtract 379 from both sides
60X = 75
Divide both sides by 60
X = 1.25