There are 230 tons of grain in the two granaries. Later, 50 tons are transported out of granary a, and 20 tons are transported into granary B. at this time, the grain in granary B is three times as much as that in granary a, and how much is there in each granary A and B

There are 230 tons of grain in the two granaries. Later, 50 tons are transported out of granary a, and 20 tons are transported into granary B. at this time, the grain in granary B is three times as much as that in granary a, and how much is there in each granary A and B

3+1=4
230-50+20=200
200/4=50
50+50=100
50*3=150
150-20=130
A: there used to be 100 tons for a and 130 tons for B