Answer:
recycled: 10 pounds
cardstock: 14 pounds
Explanation:
Let's call x the weight of one ream of recycled paper and y the weight of one ream of cardstock.
If 3 reams of recycled paper and 5 reams of cardstock weigh 100 pounds, we can write the following equation
3x + 5y = 100
Additionally, if 7 reams of recycled paper weigh as much as 5 cardstock, we get
7x = 5y
So, taking into account the last equation, we can replace 5y by 7x in the first equation
3x + 5y = 100
3x + 7x = 100
Then, we can solve for x
10x = 100
10x/10 = 100/10
x = 10
Finally, we can replace x = 10 on 7x = 5y and solve for y as follows
7x = 5y
7(10) = 5y
70 = 5y
70/5 = 5y/5
14 = y
Therefore, the weight of one ream of each type of paper is
recycled: 10 pounds
cardstock: 14 pounds