Can someone explain to me how highest common factors work?

Two concentric circles have radii 6 and 14. Find the length of a chord of the larger circle that is tangent to the smaller circle.

Explain how to write and evaluate an algebraic expression. one more than the product of a number and seven decreased by five; evaluate when n=6

A statistics professor wanted to test whether the grades on a statistics test were the same for upper and lower classmen. The professor took a random sample of size 10 from each, conducted a test and found out that the variances are equal.

What is the sales price of a shirt that originally costs $34.99, if it is 25% off?

Today the temperature is 0ﾟC the temperature dropped 12ﾟC from yesterday's temperature what was yesterday's temperature

There are 12 chairs at each table for the annual parents' night dinner. Thirty-two tables are set up. How many people can be seated at these tables?

Round 2.767.545 to the nearest ten

A certain college randomly selected 30 freshman students who completed college algebra during their first semester.

Write 0.214214214 ... as a fraction.

Subtract the polynomials: 2x^2-3xy+4y^2 from 3x^2-5xy-6y^2