A chemist needs 9 liters of a 50% solution all she has is a 20% and 50% solution. How much of each does she need?

Find all real numbers s such that - 2 (s - 7) > 4s + 8. Give your answer as an interval.

For what values of n is n! less than 2^n?

What is the product? (9t-4) (-9-4)

Am I able to evaluate sin (cos^1 (7/11)) without a calculator? If yes, how? ... ?

Express 80 as a product of prime factors using index notation

Find the slope of the line 4x-7y=28

Find the value of k for which the quadratic equation 2x^-kx+=0 have equal roots

Pamela drove her car 99 km and used 9 L of fuel. she wants to know how many kilometers if you can drive with 12 L of fuel. she assumes the relationship between kilometers and fuel is proportional.

Find two consexutive odd integers such that the sum of their square is 650

Joe bought a pair of basketball shoes for $49.99 and 2 packages of sport socks for $4.79 each. How much did he spend altogether?