How Far is Charge Q1 from Point P Where the Electric Field is Zero?

[AyooNisto]

1.Two point charges, Q1 = -22 mμ C and Q2 = 51mμ C , are separated by a distance of 12 cm. The electric field at the point P is zero. How far is Q1 from P?...Sorry if my equations arent coming out right on the screen this is the first time I've posted on the forum, if you look at the thumbnail I've posted its the way I am doing the problem

2 k Q2
(x+d)^2
3. i keep getting an answer of 29 using the formula in the thumbnail

 

[haruspex]

In your working you have Q₁ = Q₂/2, which is not the case.