Answer:
John weighs 375 pounds, and Karen weighs 125 pounds.
Explanation:
The best way to solve this question is to assign the weights to variables.
Let's give variable j to John's weight and k to Karen's.
If John weighs 3 times as much as Karen, j=3k.
If 2x John's weight plus 1x Karen's weight = 875, then 2j + k = 875,
which can also be written as 6k + k = 875 since we established that j=3k and 2*3=6.
Now all we need to do to find k is solve the equation:
6k + k = 875 combine common factors
7k = 875 divide both sides by 7
k = 875/7
k = 125
Now that we know Karen's weight, we can find John's weight by using j=3k.
Plug the now known value of k in:
j=3k
j=3(125)
j=375
Now you have your pair:
j=375, k = 125.