Calculus 1 question I need help with

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

The quadratic function h(t)=-16.1t^2+150 choose the graph representation

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate.true or false?