What Leslie has is 3 pounds of Peanuts and she has used a fraction of it. That fraction is 1 7/8. To find out how many pounds more she has left, its a matter of subtracting 1 7/8 from 3 whole.
Let the leftover be called x, and you now have;
x = 3 - 1 7/8
Converting the other number to an improper fraction you now have
x = 3 - 15/8
x = 3/1 - 15/8
By using the LCM of both denominators which is 8, the expression now becomes,
x = 24/8 - 15/8
x = 9/8
x = 1 1/8
Les