Question

the total capacity of 1 carton is the same as the total capacity of 2 identical cups. If 1.8 liters of water are needed to fill up 3 identical cups and 2 identical cartons, what is the capacity of a cup? express your answer correct to 2 decimal places

Answer 1

Let x = capacity of carton
Let y = capacity of cup
According to the first statement of the problem,
x = 2y
According to the second statement,
1.8 = 3y + 2x
Now, we have the equations. What we'll do is substitute the first equation to the second:
1.8 = 3y + 2(2y)
1.8 = 3y + 4y
1.8 = 7y
y = 1.8/7
y = 0.26 L

Hope this helps :)