Can someone please help me with this problem?

What is the missing constant term in the perfect square that starts with x^2 -20x

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?

The table shows the balance of a money market account over time. write a function that represents the balance y(in dollars) after t years.