A glass is

Question

2
5
full. Then 42cm3 of orange juice is poured in.
The glass is now
4
7
full. What is the total volume of the glass?

Answer 1

Restating your question in more traditional style:

A glass is 2/5 full. Then 42cm3 of orange juice is poured in.
The glass is now 4/7 full. What is the total volume of the glass?

let volume of glass be x cm^3
(2/5)x + 42 = (4/7)x
multiply by 35, the LCD
14x + 1470 = 20x
x = 245

you have a 245 cm^3 glass

(the metric system usually uses ml for volume of liquids)