movie tks are $5.00 in advance and $9.00 at the door. The theater sold 50 more advanced tks and total sales were $1650. How many of each priced tks were sold.?

5a+9d=1650

a = d+50

5(d+50)+9d = 1650
5d + 250 + 9d = 1650
14d = 1400
. . .