Question

x[sqrt of 2] + 3x = 4

Answer 1

x (sqrt2 + 3) = 4

x = 4/(sqrt2 + 3) = 0.90616..

You can also write the answer as
4(sqrt 2 - 3)/[(sqrt2 - 3)(sqrt2 + 3)
= 4(3 - sqrt 2)/7