Answer: she uses 2 eggs for one batch of brownies and 4 eggs for one batch of cookies.
Step-by-step explanation:
Let x represent the number of eggs that she uses for one batch of brownies.
Let y represent the number of eggs that she uses for one batch of cookies.
Last month, she made 2 batches of brownies and 3 batches of cookies. This means that
2x + 3y = 16 - - - - - - - - - -1
The month before, she baked 1 batch of brownies and 1 batch of cookies, which required a total of 6 eggs. This means that
x + y = 6 - - - - - - - - - - - - - 2
Multiplying equation 1 by 1 and equation 2 by 2, it becomes
2x + 3y = 16
2x + 2y = 12
Subtracting, it becomes
y = 4
Substituting y = 4 into equation 2, it becomes
x + 4 = 6
x = 6 - 4 = 2
