3x+4y=36 y=−12x+8 what is the y and and what is the x

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

One line passes through (-7,-4) and (5,4) . another line passes through the point (-4,6) and (6,-9)

What is the frequency of the sinusoidal graph?