Question

there is a 750 ml bottle of concentrate orange squash it is enough to make fifteen 250 ml glasses of diluted orange drink how much water is needed to make 10 litre of this drink

Answer 1

$15 \times 250 \ ml=3750 \ ml$
Fifteen 250 ml glasses contain 3750 ml of the drink, and 750 ml of orange squash.
$3750 \ ml - 750 \ ml=3000 \ ml$
There are 3000 ml of water in 3750 ml of the drink.

3000 ml of water - 3750 ml of the drink
x l of water - 10 l of the drink

$\frac{3000 \ ml}{3750 \ ml}=\frac{x \ l}{10 \ l} \\ 3750x=10 \times 3000 \\ 3750x=30 000 \\ x=8$

8 litres of water are needed to make 10 litres of this drink.