Evaluate f(x) = √(x), when x = 9. Please show how you get the answer!

One integer is 8 times another. if the product is 72, then find the integers

Florence price's brownies and more sells all types of cookies and pastries. on tuesdays, they markdown all brownies 75% to a sale of $1.50 a dozen. find the selling price and the markdown of a dozen brownies.

With alll of except for the 2 that i did already