Can you Explain this question?

No. of banners made by 1 blue bolt
= (10 yd) / (1/4 yd)
= 10 × 4
= 40
No. of blue bolts needed to make 500 banners
= 500/40
= 12.5
Hence, 13 blue blots were purchased.

No. of banners made by 1 white bolt
= (12 yd) / (3/8 yd)
= 12 × (8/3)
= 32
No. of white bolts needed to make 500 banners
= 500/32
= 15.625
Hence, 16 blue blots were purchased.

The greatest number of banners could be made by the extra blue bolt
= (13 - 12.5) × 10 / (1/4)
= 5 × 4
= 20

The greatest number of banners could be made by the extra white bolt
= (16 - 15.625) × 12 / (3/8)
= 4.5 × (8/3)
= 12 < 20

The blue material is in excess, and 12 extra banners can be made.

The answer: A. 12

To make 500 banners they would originally have needed:-
Blue: 500 * 1/4 = 125 yards
White: 500 * 3/8 = 187.5 yards

Cheaper material if blue in multiples of 10 and white in multiples of 12
Blue: Nearest next multiple of 10 is 130 yards
White: Nearest next multiple of 12 is 16*12 = 192

Extra material was 5 yards blue and 4.5 yards of white
5 yards is 20 * 1/4 yard
4.5 yards is 12 * 3/8 yard
The could make 12 extra blue and white banners.
They would have 2 yards of blue material unused.
Answer: A 12 extra banners