16a^2+21a+9=6a^2 solve the equation for all real solutions

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?

Ageologist had two rocks on a scale that weighed 4.6 kilograms together.rock a was 0.5 of the total weight.how much did rock a weigh?

Kendra had twice as much money as kareem. kendra later spent $8 and kareem earned $6. by then,the two had the same amount of money. how much money did each have originally?