Respuesta :

EXPLANATION

Given the operation:

28------> rounded to 30

56-------> rounded to 50

76 ------> rounded to 80

Now, we can mentally calculate that:

3x5= 15 so 30x50 = 1500 (two zeros)

15x8 = 120 so,

1500x80 = 120,000

The answer is 144,000.