Mathematics for IGCSE & O level - Ratio And Proportion (Section 5 - No. 48)
If the ratio of two quantities is 5:8, then
The first quantity is greater than the second quantity.
The second quantity is 8/5 times the first quantity.
The first quantity is 5/8 of the second quantity.
The sum of the quantities is divisible by 13.
Uitleg
The second quantity is more since the ratio is 5:8. Hence second quantity is 8/5 times the first. Thus first quantity is 5/8 of the second. and 5+8=13, the sum is divisible by 13.