Plz help, my mom is working, and can't help me!

What is the smallest integer n such that n\sqrt{2} is greater than 20

Two blends of tea are mixed to make a blend that will be sold at the fair. black tea sells for $2.20 per pound and orange pekoe tea sells for $3.00 per pound. how much of each should be used to obtain a 4lb blend selling for $2.50 per pound?

Is a positive integer raised to a negative power always positive