A question about electric charge?

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Question : http://postimg.org/image/g1y6ko6aj/

I am bad at Physics. I have no idea how to do it even though I have studied my lecture notes. Can anyone help me with detailed explanation?
I want know if qb = qa or the force (blue arrow) is equal to the force(red arrow), and why?

[Deadpool]

Force F = (q1*q2)/(4*pi*epsilon)*r^2

Also given Fa*cos30 + Fb*cos30 = 733.1N where Fa is the force due to qa

We get qa + qb = 10.21*(10^-6) C = 10.21uC

Since there is no relation given between qa and qb there is no way to find qa and qb values individually

Since both the charges are attracting the positive 5uC charge, both qa and qb are negative.

In this case Fa and Fb are equal only if qa and qb are equal