let

x = lbs the original amount in the first sack

y = lbs the original amount in the second sack

There are 140 lb of flour in two sacks:

x + y = 140

If you take 1/8 of the flour from the first sack and add it to the second, there will be an equal amount of flour in both sacks:

x - (1/8)x = y + (1/8)x

by solving the system of equations:

x + y = 140

x - (1/8)x = y + (1/8)x

we find:

x = 80 lbs

y = 60 lbs

click here to see the step by step solution of the system of equations:

there are 80 lbs of flour in the first sack and 60 lbs of flour in the second sack.