At a lunch stand each hamburger has 60 more calories than each order of fries. If 3 hamburgers and 4 orders of fries have a total of 1580 calories how many calories does a hamburger have

H = Hamburger

f = fries

3 h + 4f = 1580 calories - equation 1

If each order of hambruger is 60 cal more than fries then we turn it into ...

h - f = 60 calories - equation 2

And flip over the equation to make h the subject, it is possible to do it for f but ny preference is h.

h = 60 + f - equation 3

3 (60 + f) + 4 f = 1580 cal

180 + 7f = 1580 cal

7f = 1580 - 180 cal

7f = 1400 cal

f = 1400 / 7

f = 200

So each order of fries have 200 Calories

We take equation 1 and substitute it into the equation.

3h + 4 (200) = 1580 cal

3h + 800 = 1580 cal

3h = 1580 - 800 cal

3h = 780

h = 260

Each order of a hambruger has 260 calories to check the answer we substitute again.

3 (260) + 4 (200) = 1580

780 + 800 = 1580

Answer is correct