Daily earnings from pairwise totals: A, B and C together earn ₹ 375 in 5 days. A and B together earn ₹ 450 in 10 days. A and C together earn ₹ 200 in 4 days. Determine the daily earning (per day) of each: A, B and C.

Introduction / Context:
We are given combined earnings over multiple-day periods for different pairs and for all three together. The trick is to convert each total into a per-day figure and then solve the resulting system of linear equations to get individual daily earnings.

Given Data / Assumptions:

• (A+B+C) over 5 days = ₹ 375 ⇒ per day = 75
• (A+B) over 10 days = ₹ 450 ⇒ per day = 45
• (A+C) over 4 days = ₹ 200 ⇒ per day = 50

Concept / Approach:
Let a, b, c be daily earnings. Then we have three equations: a+b+c=75, a+b=45, a+c=50. Subtract to obtain b and c, and then find a.

Step-by-Step Solution:
a + b + c = 75a + b = 45 ⇒ c = 75 − 45 = 30a + c = 50 ⇒ a = 50 − 30 = 20Then b = 45 − a = 25Hence daily earnings: A = 20, B = 25, C = 30

Verification / Alternative check:
Check pairs: A+C = 20+30=50 (matches); A+B = 20+25=45 (matches); A+B+C = 75 (matches).

Why Other Options Are Wrong:
Other permutations present different assignments and do not satisfy all three equations simultaneously.

Common Pitfalls:
Forgetting to convert totals to per-day values; algebraic slip when subtracting equations; swapping the identities of b and c.

Final Answer:
20 , 25 , 30