fifteen boys took 12 hours to weed a plot of land. If nine boys work at the same rate how long will it take them to weed the same plot of land.

Helll ! 1,400 tons of wheat of two different varieties was delivered to the silo. when processing one variety, there was 2% of waste and 3% during the processing of the second variety of wheat. after the processing, the amount of remaining wheat was 1,364 tons. how many tons of each variety of wheat was delivered to the silo?