Respuesta :

80*30/100 = 24 lambs give birth to 2 lambs
80-24  = 56 lambs give birth to 1 lamb
56+2(24) = 56+48 = 104 lambs

hope it helps :)
104 lambs born.
80 times 30% is 24.
24 times 2 is (48)
Then there are 56 sheep left because 70% of 80 is (56)
48+56=104