We know that 5 lbs of apples cost $2.99
To know how much do 3 lbs of apple cost, you can use cross multiplication
If 5 lbs cost $2.99
Then 3 lbs cost $x
The proportion between the price and the number of apples is the same, you have to calculate it as:
[tex]\begin{gathered} \frac{2.99}{5}=\frac{x}{3} \\ (\frac{2.99}{5})\cdot3=x \\ x=1.794 \end{gathered}[/tex]3 lbs of apples cost $1.79