Question 1022114
<pre>
Here's the easiest way to solve the problem.  No algebra needed.
Just basic math.  Not only that but also too much information is 
given.  We don't even need the first sentence at all.

The times given in the other sentences are 1 2/3 hours, and 
1 hour.

1 2/3 hours is 1 hour 40 minutes or 100 minutes.

So the times given are 100 minutes and 60 minutes.

The easiest common multiple of those is 600 minutes or 10 hours.
So let's take everything up to 10 hours.
</pre>
Penny and Lenny can eat a whole gallon of ice cream together 
in 1 (2/3) hours.
<pre>
That's 100 minutes, so in 600 minutes (or 10 hours) Penney 
and Lenny can eat 6 gallons. 
</pre>
All three together can eat a whole gallon of ice cream 
together in 1 hour. 
<pre>
So in 10 hours they can all three eat 10 gallons.

Since in 10 hours Penney and Lenny would eat 6 of those 10 
gallons, Jenny would eat the other 4.  Jenny can eat 4 
gallons in 10 hours, so Jenny could eat 1 gallon in 1/4th 
of 10 hours or 2 1/2 hours.  

See?  We didn't need the first sentence, or any algebra, 
at all. :)

Edwin</pre>