Each room is 52 square meters. The formula is: Class I can draw X square meters a day, Class II can draw x- 10 square meters a day, and a room is Y square meters. The formula is: 1 3x=8y-50。
Formula: 2. 5(x- 10)= 10y+40。
X=(8y-50)/3 comes from the formula 1.
According to formula 2, X=2y+ 18.
Then (8y-50)/3=2y+ 18 gives y=52 square meters.
Abs are 72km apart.