How much water should we add to 35kg of sugar syrup to change it's concentration from 30% to 25%

Water = 1/5 of the volume of the syrup

Step-by-.step explanation:

Suppose we had  1000 cm^3 of syrup  and the new volume after adding water is x cm^3.  Now the amount of sugar stays the same so we have the equation 35 * 1000 =  25 * x

x = (30 * 1000) / 25 =  30,000 / 25

= 1200 cm^3

So we need to add 200 cm^2 of water .

In general terms,  we need to add water which equals 1/5 of the volume of the syrup,