The average weight of T. U and V is 42 kg. If the average weight of T and U is 40 kg and the average weight of U and V is 36 kg, then what is the weight of U?

Let the individual weights (in kg) of T, U and V be $$T$$, $$U$$ and $$V$$ respectively.

Average of T, U and V is 42 kg: $$\frac{T+U+V}{3}=42 \implies T+U+V = 126$$ $$-(1)$$

Average of T and U is 40 kg: $$\frac{T+U}{2}=40 \implies T+U = 80$$ $$-(2)$$

Average of U and V is 36 kg: $$\frac{U+V}{2}=36 \implies U+V = 72$$ $$-(3)$$

Add $$(2)$$ and $$(3)$$: $$T+U + U+V = 80 + 72 \implies T + 2U + V = 152$$ $$-(4)$$

Subtract $$(1)$$ from $$(4)$$: $$(T + 2U + V) - (T + U + V) = 152 - 126$$ $$U = 26$$

Hence, the weight of U is 26 kg.

Option A which is: 26 kg