according to the HL theorem for right-triangles, one leg and the hypotenuse must be equal, what does that mean?
well it means that 3y = x + 3, and that y + 1 = x, when does that happen anyway? let's see,
[tex]\bf \begin{cases}
3y=x+3\\
y+1=\boxed{x}
\end{cases}\implies 3y=\boxed{y+1}+3\implies 3y=y+4
\\\\\\
2y=4\implies y=\cfrac{4}{2}\implies y=2\\\\
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\textit{and since we know that }y+1 =x\implies (2)+1=x\implies 3=x[/tex]
