The solution of the problem 2.2 cr 2 from the problem b

The solution of the problem 2.2 cr 2 from the problem b

Task 2.2.
In the tops of a square with a side of 0.5 m there are charges of the same size. In the case where two adjacent charges are positive and the other two are negative, the field strength at the center of the square is 144 V / m. Determine the charge.