Help! Please Can you tell me how you do this? Thank you!

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

Write an inequality and solve each problem.for exercises 11 and 12, interpret the solution.

You deposit $5000 each year into an account earning 3% interest compounded annually. how much will you have in the account in 30 years?