SAT Right triangles Question

$$\mathrm{y}=2{\mathrm{x}}^2-23\mathrm{x}+64$$ $$\mathrm{y}=\mathrm{x}+\mathrm{a}$$ In the given system of equations, a is a constant. The graphs of the equations in the given system intersect at exactly one point, $(\mathrm{x},\mathrm{y})$ , in the xy-plane. What is the value of x?