Answer:
A budget constraint is the amount of goods and service that a person or firm can purchase given their income.
In this case, the budget constraint of Sam and Amanda is determined by their income: that is to say, their monthly grocery budget, which is $100 per month.
Because a dozen organic egg costs $5, and a frozen pizza costs $10, if we suppose that Sam Amanda will spend half their income on each item, their budget constraint will allow them to buy the following amounts:
$50 / $5 = 10 dozen organic eggs
$50 / $10 = 5 frozen pizzas.