1.
The inequality that the question represents, is the following
[tex]2.5+5B\leq21[/tex]
2.
We must calculate the inequality when it is equal to $ 21, that is, the following equation would remain
[tex]\begin{gathered} 2.5+5B=21 \\ 5B=21-2.5 \\ B=\frac{18.5}{5} \\ B=3.7 \end{gathered}[/tex]
Therefore, since it is not enough to buy all 4, you can buy 3 bags, the total of avocado would be:
[tex]A=3\cdot3=9[/tex]
in total, the largest number of avocados is 9
