In the given question, we already know
Work done = 150 joules
Force = 120 Newton
Now we know from the study of physics that
Distance (D) = Work done / Force
(a) To find the height upto which the backpack has been lifted,
D = Work done / Force
= 150 / 120
= 15 / 12
= 5 / 4
= 1.25
So the backpack was lifted to a height of 1.25 metres.
(b) Now we have the find the weight of the backpack in pounds
We know that 1 pound = 4.448 Newton
So if
4.448 Newton = 1 pound
Then
120 Newton = (120 / 4.448) pounds
= 26.978 pounds
So the backpack weighed 26.98 pounds.