Make a equation to solve this problem:
a number is 1/7 of another number. the difference of the numbers is 18. (assume that you are subtracting the smaller number from the larger number) find the numbers.

X=1/7y
y-x=18
add x to both sides
y=18+x
subsitute
x=1/7(18+x)
multiply both sdies by 7
7x=18+x
subtract x form both sdies
6x=18
divide by 6
x=3

subsitute
y=18+3
y=21

x=3
y=21

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)