Last week , landon ate a total of 19 cookies and cupcakes . if the cookies contain 140 calories each the cupcakes contain 275 calories each, and he consumed a total of 3605 calories , how many cookies did he eat?

he ate 12 cookies

Step-by-step explanation:

Let x represent the number of cookies that Landon ate last week.

Let y represent the number of cupcakes that Landon ate last week.

Last week , Landon ate a total of 19 cookies and cupcakes. This means that

x + y = 19

If the cookies contain 140 calories each the cupcakes contain 275 calories each, and he consumed a total of 3605 calories, it means that

140x + 275y = 3605 - - - - - - - - - -1

Substituting x = 19 - y into equation 1, it becomes

140(19 - y) + 275y = 3605

2660 - 140y + 275y = 3605

- 140y + 275y = 3605 - 2660

135y = 945

y = 945/135 = 7

x = 19 - y

x = 19 - 7 = 12