The most simplistic equation

Solve the equation for x.3(6x - 1) = 12 i've tried doing the math and i can't find out what i'm doing wrong

Two numbers have a sum of -19. one number is x. what expression represents the other number?

Find the volume of the solid whose base is the region bounded by f(x), g(x) and the x-axis on the interval [0, 1], and whose cross-sections perpendicular to the y-axis are squares. your work must show the integral, but you may use your calculator to evaluate it. give 3 decimal places for your answe