physics
posted by tina .
A 190 kg object and a 490 kg object are separated by 0.400 m. At what position (other than an infinitely remote one) can the 35.0 kg object be placed so as to experience a net force of zero?
 m from the 490 kg mass
I do not understand how to attack this problem. pls help.

call our mass m, the 35 does not matter, could be any amount.
we are x meters from the 190 kg
and
we are (0.4  x) meters from the 490 kg
we have to be on the line between them so we are not pulled sideways
so
Fleft = G(190)m /x^2
Fright = G(490)m/(.4x)^2
so for equal and opposite
190/x^2 = 490/(.4x)^2
solve the resulting quadratic for x 
when i try and solve this i get 300x^2+152x30.4
how would i solve after this?