Total calories : 363 kcal
Complete question
A cheeseburger from a fast-food restaurant contains 19g of fat, 20g of carbs, and 28g of protein. How many kcal of energy does the cheeseburger contain?
We convert each gram of composition to kcal :
1 gram of fat = 9 kcal
1 gram of carbs = 4 kcal
1 gram of proteins = 4 kcal
[tex]\tt 19\times 9~kcal=171~kcal[/tex]
[tex]\tt 20\times 4=80~kcal[/tex]
[tex]\tt 28\times 4=112~kcal[/tex]
[tex]\tt 171+80+112=363~kcal[/tex]