Answer:
8 pairs of large glasses and 12 pairs of small ones
Step-by-step explanation:
Let's say the number of large frames she buys is l, and the number of small frames is s. She buys 20 frames of assorted sizes, but they can only be small or large. Therefore, s + l = 20.
Next, the total cost of large frames is 12 dollars for each frame. Therefore, the total cost for the large frames is equal to 12 * l. Similarly, the total cost for the small frames is equal to 5 * s. The total cost of all frames is equal to 156, so
12* l + 5 * s = 156
s + l = 20
In the second equation, we can subtract l from both sides to get
s = 20 - l
We can then plug that into the first equation to get
12 * l + 5 * (20-l) = 156
12 * l + 100 - 5*l = 156
subtract both sides by 100 to isolate the variable and its coefficient
12 * l - 5 * l = 56
7 * l = 56
divide both sides by 7 to isolate the l
l = 8
The woman buys 8 pairs of large glasses. The number of small glasses is equal to 20-l=20-8=12
