An electron is released from rest in a uniform electric field. the electron accelerates vertically upward, traveling 4.50m in the first 3.00μs after it is released.

If you are looking for the strenght of the electric field, then what you need to do is the following calculation:
E=F/q, and F=ma,
thus E=(ma)/q=(m· 2· x)/(t 2· q) = [(9.11×10-31kg)·2·(4.5m)] / [(3×10-6s)2(1.6×10-19C )]= 5.69 N/C 
That is the strenght. Now that you know that the force is up and that the electron is negative then the projectile motion principles must be used
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