Respuesta :

430 / 1500 = x / 75,000
cross multiply
1500x = (75000)(430)
1500x = 32250000
x = 32250000/1500
x = 21,500 lbs of pebbles are needed
430p   1500SF
860p    3000SF
1290p   4500SF
1720      6000SF
2150      7500SF

The answer is 2,150