3. One gram of protein contains 7 calories and one gram of fat contains 9 calories. If a cheeseburger has a total of 500 calories and has 9 grams of protein, write an equation that can be used to find the number of grams of fat in the cheeseburger.

There is 48.5 grams of fat in the cheeseburger. We know 500= amount of protein + amount of fat which translate to 500= p x 7 + f x 9 where p = protein f= far and 7 and 9 are the calories for protein and fat. We know there are 9 grams of protein so we can add that in the equation. 500= 9 x 7 + f x 9. Which simplifies to 500= 63 + f x 9. We know the calories of protein in the cheeseburger is 63 so we subtract that from the total amount of calories. 500-63= 437. 437 is the total amount of calories in fat. To figure out grams of fat you continue. 437=f x 9. Then you divide 9 on both sides where you get 48.5=f where f is the grams of fat. There are 48.5 grams of fat in the cheeseburger.