Any answers? explain too please

Which is the most efficient first step to solve x in the equation 3.7x - 18 = -4.3x -34 a. add 3.7x to both sides of the equation. b. add 4.3x to both sides of the equation. c. subtract 18 from both sides of the equation. d. subtract 34 from both sides of the equation.

What is the absolute value of the complex number -4-sqrt2i

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).