Final answer:
To find the cost of a bag of chips, we set up a system of equations with the given information. We solve this system algebraically to determine that the cost of one bag of chips is $4.
Step-by-step explanation:
The subject of this question is mathematics, specifically algebraic word problems that involve a system of equations. To find the cost of a bag of chips, we need to establish a system of equations considering that Ms. Watson buys 3 pizzas and 12 bags of chips for a total cost of $72 and that each pizza is $4 more than each bag of chips.
Let's assign variables to the unknowns: Let c be the cost of one bag of chips and p be the cost of one pizza. According to the problem, p = c + $4. Ms. Watson's total spending is reflected in the equation 3p + 12c = $72. Now we can substitute the first equation into the second to find the cost.
Using the first equation, we express p in terms of c: p = c + 4. Substituting this into the second equation gives us 3(c + 4) + 12c = 72.
Expanding this we get 3c + 12 + 12c = 72, which simplifies to 15c + 12 = 72. Subtract 12 from both sides to get 15c = 60.
Finally, we divide both sides by 15 to find the cost of a bag of chips: c = $60 / 15, therefore c = $4. This is the cost of one bag of chips.