Final answer:
To solve the system of equations for p and a, we need to write two equations based on the given information and use substitution or elimination method to solve the system. Additional information or equations are required to find the numerical values of p and a.
Step-by-step explanation:
To solve the system of equations for p and a, we need to write two equations based on the given information. Let's say Al bought x bags of pretzels and Erika bought y cans of almonds. The first equation will represent the total number of bags of pretzels and cans of almonds they bought: p = x + y. The second equation will represent the cost of the snacks: 2p + 3a = 20.
Now we can solve the system of equations using substitution or elimination method. Let's use substitution method:
Substitute the value of p from the first equation into the second equation: 2(x + y) + 3a = 20. Simplify the equation: 2x + 2y + 3a = 20.
Since we have three variables, we need one more equation to solve for all the variables. We will need additional information or equations to proceed with finding the numerical values of p and a.