Respuesta :

1 4/8
3/8 + 3/8 + 3/8 + 3/8=  12/8 = 1 4/8 or 1 1/2
If the puppy gained 3/8 lb each week for 4 weeks, then all together he gained...

3/8 * 4 = 12/8 = 1 1/2 lb

(Hope that's what you were asking... :) )