A very long uniform line of charge has charge per unit length 3.70 µC/m and lies along the x-axis. A second long uniform line of charge has charge -2.20 µC/m per unit length and is parallel to the x-axis at y = 0.400 m. What is the net electric field (magnitude and direction) at the following points on the y-axis?

a) y=0.200m
b)y=0.600m

For A I got 5.31*10^5 and it was correct but for B I got 8.69*10^5 and its wrong.

How do you do part B?