300 calories are burned for 60 minutes
Solution:
Given that, Antonio burns 75 calories for every 15 minutes he rides his bicycle
To find: calories burned if he rides his bicycle for 60 minutes
From given information,
For every 15 minutes, 75 calories is burned
Therefore, for 1 minute,

So in 1 minute, 5 calories are burned
We have to find the calories burned for 60 minutes
Let "x" be the calories burned for 60 minutes
1 minute = 5 calories
60 minutes = x calories
This forms a proportion and we can solve the sum by cross multiplying

Thus 300 calories are burned for 60 minutes