[tex] \frac{2y+b}{t}=t [/tex]
multiply both sides by t
[tex] \frac{(2y+b)t}{t}=tt;t \neq 0 [/tex]
simplify
[tex]2y+b=t^2;t \neq 0[/tex]
subtract b from both sides
[tex]2y+b-b=t^2-b;t \neq 0[/tex]
simplify
[tex]2y=t^2-b;t \neq 0[/tex]
divide both sides by 2
[tex] \frac{2y}{2}= \frac{t^2}{2}- \frac{b}{2};t \neq 0 [/tex]
simplify
[tex]y= \frac{t^2-b}{2};t \neq 0 [/tex]
Hope this helps :)