Mr Hall sold 78 items at a car boot sale. 35% of his items did not sell,
How many items did Mr Hall have for sale?

120

A 35% decrease of (items he had for sale) is 78.
So 65% of (items he had for sale) is 78.

This means that 0.65 x ? = 78
We can work this out by doing 78/0.65 which is 120.

So I believe Mr Hall had 120 items for sale.

This is called reverse percentages if you want to watch some videos explaining it. Hope this helps!

C. 40,320 just did the math right now