Three charges are placed at three corners of a square as shown in Figure 5. Find the electric field strength at point A.

Given answer is 8.23x10^5 N/C and makes an angle 45 degree below –x-axis.

I can't get the answer.First I start the formula E=k(q1xq2)/r^2 and x and y component then I don't know how and what formula to use but I got try my best to do this question but I still unable to find solution.Can someone guide me with solution nicely.Thanks in advance