A dealer sold 200 tennis racquets. Some were sold for $33 each, and the rest were sold on sale for $18. The total receipts form these sales were 4.800. How many racquets did the dealer sell at $18 each.
Let the number of $33 rackets sold = R
The number of $18 rackets sold =200 - R
33R + 18*[200 - R] =4,800 (I assumed your 4.800 to mean $4,800).
33R + 3,600 - 18R =4,800
15R =4,800 - 3,600
15R =1,200
R =1,200 / 15 = 80 rackets priced at $33 were sold.
200 - 80 = 120 rackets priced at $18 were sold.