Help with an Algebra 2 word problem

[MACHO-WIMP]

1. The problem statement, all variables and given/known data
a glassblower can produce a set of simple gasses in about 2 hours. when the glassblower works with an apprentice, the job takes about 1.5 hours. How long would it take the apprentice to make a set of glasses when working alone?


2. Relevant equations
none


3. The attempt at a solution
I'm really having trouble with this question. The back of the book says that it will take the apprentice 6 hours to do so, but I don't have the slightest clue of how they got there.

[NascentOxygen]

One way to solve this is to say that the glassblower works at a rate of G units of work per hour,
and the apprentice works at A units of work per hour. So you can then say their combined rate of working is going to be ..... units of work per hour.

Then use the information you are given to form an equation or two, and solve for A.

[MACHO-WIMP]

thank you SOOOO much NascentOxygen! I have been staring at this problem for a long time. again, thanks.