For individual, round-trip discount $10\%$ on TOTAL fare.
So, for each person, discount for Total fare of Rs. $200 = 200 \times 0.1 =20.$
So, for $5$ members discount $= 100$ rupees
For $5$ member group they is extra $5\%$ discount on TOTAL fare i.e., $5\times 200 \times 5\%= 50 $ rupees.
Total discount is $100+50=150.$
They have to pay $5 \times 200 - 150 = 850$ rupees