Mr. Loh had some sneakers in his shop. 3/8 of them were red, 3/10 of the remainder were black, and the rest were white.
The table above shows the amount he earned per pair of shoes. The number of red shoes sold to the number of black shoes sold to the number of white shoes sold was 1 : 2 : 4. In total, he sold one quarter of the shoes and earned $1,080. How many pairs of white shoes did have at first ?