What is the equation? 8th math

Read the following two statements. then use the law of syllogism to draw a conclusion. if the tv is too loud, then it will give me a headache. if i have a headache, then i will have to rest.

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

How do you solving the solution of each system using elimination?