A music download website sells singles and albums. The music download website makes 1000 sales in one hour.
Singles cost 50p to download. Albums cost £4.50 to download. The income for this hour is £1500.
How many singles does the website sell in this hour?
0.50 s + 4.50 a= 1500
0.5 s + 4.5 (1000-s) = 4500-4s=1500
4s= 3000 and s=3000/4=750
In this hour, the website did sell 750 single.