One grade of tea worth $3.90 per pound is to be mixed with another grade worth $2 per pound to make 20 pounds that will sell for $2.76 per pound. How much (in lb) of each grade of tea must be used?

lb

$3.90 tea= lb

$2 tea= lb

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6