We have to call $10 to win $25 therefore 10:25.

To work this out as a percentage we take both sides of the ratio and add them together 25+10 and divide the left hand side by the result, then multiply by 100. Which makes 10/35*100=28%.

THAT IS HOW YOU CONVERT A RATIO INTO A PERCENTAGE

RATIO A:B = A/(A+B)*100

GCSE maths fail.