Question

1440 tons of grain were brought to a silo over two days. On the second day, 80% of the amount of the grain delivered during the first day was brought in. How many tons of grain were delivered to the silo on the first day?

Answer 1

Answer is 800 
because if you do
1440=0.8t+t
1440=1.8t
800=t 
so the first day is 800 tons and the second day is 640 tons