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.
Step-by-step explanation:
To see if Sarah is correct, let's replace the y in the equation with 42 and the x with 10:
The height of the object is EQUAL to the height of the model. We can see this in advertising when for example cereal is being advertised and on the box is says "actual size" because the cereal is drawn to scale.
