We have the next diagram
We have
[tex]\sin (A)=\frac{CB}{AB}=7x-2[/tex]then we have
[tex]\cos (B)=\frac{CB}{AB}=5x+6[/tex]because the trigonometric functions have the same ratio, we can do the next equality.
[tex]7x-2=5x+6[/tex][tex]7x-5x=6+2[/tex]we sum similar terms
[tex]2x=8[/tex]we isolate the x
[tex]x=\frac{8}{2}[/tex]the value is x=4
