A solution of sugar is obtained by mixing 200g of its 25 % solution...

Mass of solution $= 200 + 500 = 700g$

$25$ of sugar solution means $100g$ solution contain $25g$ sugar

$40$ of sugar solution means $100g$ solution contain $40g$ sugar

Mass of sugar $= 0 . 25 \times 200 + 0 . 40 \times 500$

$= 50 + 200 = 250g$

Mass $$ of resulting solution

$= \dfrac{250}{700} \times 100 = 36$