Select the property that allows 3=x

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

What percent of the circle below is shaded?

Aquadratic equation in standard from is written ax^2= bx+c, where a, b and c are real numbers and a is not zero?