Answer:

2 pounds of ham
Step-by-step explanation:
<u>1) Construct an equation</u>
Let
be equal to the number of pounds of turkey.
Let
be equal to the number of pounds of ham.
We know that every pound of turkey costs 6 dollars, so the amount of money Lucy must spend on turkey is
.
We also know that every pound of ham costs 4.50 dollars, so the amount of money Lucy must spend on ham is
.
However, because 25 dollars is her budget,
and
must be equal to 25.

<u>2) How much ham can Lucy buy if she bought 2.5 pounds of turkey?</u>

Plug in 2.5 as 

Subtract both sides by 15

Divide both sides by 4.5

Therefore, Lucy can buy 2 pounds of ham if she bought 2.5 pounds of turkey.
I hope this helps!