Can someone me i am stuck like chuck

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?

Enter the number of complex zeros for the polynomial function f(x) = x 4+ 5x² +6

Solve the given system of equations. 2y= -x+9 , 3x-6= -15