A batsman played with an average of 78 runs per match in first 28 matches. In the next 14 matches, he scored runs win an average of "x" runs per match so that his overall average becomes 80 runs per match. Find the value of "x".

5x-140/x=-15

the price of a stock drops $3 each day for 7 days. The stock was worth $50 before the price began dropping. What is the price of the stock after the price dropped in price.

Wouldn't t=4 days seeing as the question said "Three days later"?