We are told that she drove 3 times as many miles in March as she did in January. This means that to get the number of miles she drove in January, we divide the number of miles she drove in March by 3:
900 / 3 = 300 miles
We are also told that she drove 4 times as many miles in February than January. This means that to get the number of miles she drove in February, we multiply the number of miles she drove in January by 4: