200 pupils are taking a school trip. Some are flying, some are taking the bus. There are three times as many boys going as girls. One third of the boys going are flying. How many boys are getting the bus?
x is number of boys. y is number of girlsx + y = 200x = 3y4y = 200y = 50x = 1502/3 * 150 = 100 boys getting the bus
