ask help for 2 math JJ, THANKS

dreamtrue

1) A retailor bought 100 radios for $30 each, sold n radios for $50 each, and sold the left for x bucks each, made a total profit of $1500, then ask about whether x > $40 or not?
(1) n > 6
(2) n < 8

2) A researcher was doing an experienment, and got 84 numbers of data and their sum correctly, but divided the sum by a wrong number x (other than 84) and got the average 400, ask whether we could figure out the correct averageD)
(1) The wrong number x is 77
(2) If the sum were divided by 66, the average would be 88