<span>Sarah's conclusion is invalid, because she is testing two variables at once without a control value. In order for the experiment to be valid, Sarah should either apply the same soil to both areas (assuming they are, in fact, the same). Or, she should water both equally. At this time, we don't know if B grew "better" due to the brand or the amount of water received.</span>
Step-by-step explanation: To find what c equals, we must flip the solution around and subtract it. When we take 100 - 26, we get 74. Therefore, c = 74. I hope this helped! :)
