'Seventeen less than a number a' can be written algebraically as a-17.
Similarly, 2 times a number b is 2*b=2b
Therefore, the left side of the equation is
[tex]2x-17[/tex]And the right side of the equation is 6. Thus, the whole expression is
[tex]2x-17=6[/tex]The answer is 2x-17=6, and, once solved, x=23/2