Writing equations in slope intercept form

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 price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c