What is the simplified version of 15√15 divided by √30? (not in decimal form)

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.

Extra points! find the missing dimension! need asap

Which is the focus of a parabola with equation y2=4x