PLEASE HELP! Electric Fields for 3 charges

Referring to the diagram, Q1 = 7.00°C, Q2 = -7.00uC, Q3 = 7.00uC, y = 4.00cm and x = 5.00cm. What is the magnitude
of the electric field at Q2, due to Q1 and Q3?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?