Question

# 50% discount + 40% discount=-----discountA. 60B. 70C. 80D. 90

The total discount is given by the formula $\begin{gathered} = \left( {x + y - \dfrac{{xy}}{{100}}} \right)\% \\ = \left( {50 + 40 - \dfrac{{2000}}{{100}}} \right)\% \\ \end{gathered}$
The total discount=$\left( {90 - \dfrac{{2000}}{{100}}} \right)\% = 70\%$