How to calculate the velocity? the answer is 5.4 m/s I need the explication

Answer: sq. root of .735
Explanation:
multiply two on both sides.
(2) *2,94 = (0,200 * v^2) (2)
588 = 0400 * 2v^2
divide by 400 on both sides
1.47 = 2v^2
divide by 2 on both sides
.735 = v^2
take square root of both sides
[tex]\sqrt{.735)[/tex] or .85732141