Question

And put her dog Simon on a diet for three weeks. Simon lost 3 pounds the first week, gained 1.75 pounds the second week, and lost 2.5 pounds the third week what was his net weight gain or loss ?

Answer 1

This is easy enough for you to do on your own. 

Answer 2

Simon's net weight loss is 3.75 lbs
-3 + 1.75 - 2.5 = -3.75