/sci/ - Science & Math

Guys how do i solve 55?
The result should be (4,3)
But if i put y=3/4 in the upper equation and then simplify it for the quadratic equation, i get a fucked up root ( i get 6.51950199 wtf)
I don't know where i went wrong, pls halp

Retard here, what am i doing wrong in this quadratic equation?
If is simplify the first equation i get x^2+y^2-2x-14y+25=0
But if i enter y=3/4 from the second equation to the simplefied first one and then multiple by the cummon i get 7x^2-50x+100, and that doesn't make sense.
The real anwser is (4,3), idk where my mistake is