The mass per unit length of a uniform wire is $0.135 \mathrm {~g} \mathrm {~cm} ^ { - 1 }$. A transverse wave of the form $y = - 0.21 \sin ( x + 30 t )$ is produced in it, where $x$ is in meter and $t$ is in second. Then, the expected value of tension in the wire is $x \times 10 ^ { - 2 } \mathrm {~N}$. Value of $x$ is $\_\_\_\_$ (Round-off to the nearest integer)