75 gm of sugar solution has 30% sugar in it. Then the quantity of sugar that should be added to the solution to make the quantity of the sugar 70% in the solution is :

Answer: Option B

Sugar in original solution = $$\frac{75\times 30}{100}$$  = 22.5 gm
Let m gm of sugar be mixed.
$$\therefore \frac{22.5+\text{m}}{75+\text{m}}\times 100=70$$
⇒ 2250+ 100m = 75 × 70 + 70m
⇒ 2250 + 100m = 5250 + 70m
⇒ 30m = 5250 - 2250 = 3000
⇒ m = $$\frac{3000}{30}$$  = 100 gm