Final answer:
Alonso can buy 3 bags of avocados after purchasing eggs for $2.50, leaving him with $18.50. As each bag costs $5, he can afford 3 bags which totals to $15, equating to 9 avocados.
Step-by-step explanation:
To determine how Alonso can get 3 bags of avocados or 9 avocados with the money he has, first, we calculate the cost of the eggs he buys. Alonso buys eggs for $2.50, which leaves him with $21 - $2.50 = $18.50 remaining. Next, we examine the cost of avocados. The store sells avocados in bags of 3 for $5 per bag. The number of avocado bags Alonso can afford is determined by dividing the remaining money by the cost per bag of avocados: $18.50 / $5 = 3.7 bags. However, since he can't buy a fraction of a bag, he can only buy 3 full bags of avocados.
The cost for 3 bags of avocados is 3 bags × $5/bag = $15. Alonso spends $15 on avocados plus $2.50 on eggs, which totals to $17.50. Therefore, Alonso can get 3 bags of avocados, which equals 9 avocados since each bag contains 3 avocados.