The number line is attached. He could use the 300ml container 3 times and the 50 ml container 2 times. The number equation would be 300(3) + 50(2) = 1000.
1 liter = 1000 ml
Dividing 1000 by 300 gives us 3. This means we would use the 300ml container 3 times. 300*3 = 900; 1000-900 gives us 100 ml left. 100/50 = 2, so we would use the 50 ml container twice.
