Question

David loves to cook! He knew 21 recipes before starting cooking school and he learns 2 recipes

every 1 one week. An equation to represent that is y = 21 + 2x where x represents number of
weeks and y represents number of recipes.
His friend Sarah believes that if he attends school for 10 weeks that means he knows 42 recipes.
Explain if she is correct.

Answer 1

Sarah is not correct because if David already knows 21 recipes and learns 2 recipes per week, then he will know only 41 recipes after 10 weeks, not 42.

Explanation:

To see if Sarah is correct, let's replace the y in the equation with 42 and the x with 10:

y = 2x + 21

42 = 2(10) + 21

42 = 20 + 21

42
`\\eq` 41

Sarah is wrong.

Answer 2

Sarah is incorrect.

Explanation:

By plugging 10 in as 'x' to the equation, we get y=21+(2*10). 2 x 10 is 20, and 20 + 21 is not 42 - it's 41. So, Sarah is incorrect.