1) Distance = speed x time
time = distance/speed
time = 8054/715 = 11.26 hours or 11 h and 15 minutes (0.26 x 60 = 15.6)
2) The mode in a statistical series is the number that is repeated most or in short the highest frequency. In you example we notice that 12 is repeated twice, whereas the others are not repeated. Then the mode is 12.
3) The cost of each game = $17.99, so with his $65 he can buy:
65/17.99 = 3.61 . Obviously he can't buy 0.61 game, then he can buy
only 3 games (3 x 17.99 = $53.97) and keep in his pocket :
65 - 53.97 = $11.03