On a number line what is the distance between 10 and -1

Use circumcenter theorem to solve for the given values

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is

The sum of a number and 5 times the number is 18.find the number