Find the magnitude of the electromagnetic force on electron?

[prokaryote]

Homework Statement

In a certain region of space, there is a uniform electric field, E = 4.28 x 104 V/m directed due east, and a uniform magnetic field B = 0.071 T, also directed due east. What is the magnitude of the electromagnetic force on an electron moving due south with a velocity of 3.09 x 106 m/s?

Homework Equations

Fb = qB(v*sinθ), where Fb is the force of the magnetic field, B is the magnitude of the magnetic field, v is the velocity.
Fb + Fe = F(electromagnetic force)

The Attempt at a Solution

I determined that the electric field would generate a westward force on the electron, and the magnetic field would exert a force into the page. I tried to use the relationship Fb + Fe = Ftotal and got 4.20*10^-14 N, but it was wrong. I'm not really sure what else to try.

 

[TSny]

You have the directions correct. Be sure to use vector addition.

 

[prokaryote]

You have the directions correct. Be sure to use vector addition.

Ok, I tried doing vector addition but I'm pretty stuck. Could you please take a look at my work and let me know if I'm completely off? I feel lost
https://imgur.com/a/0HwuI

 

[TSny]

Since the two forces are perpendicular, you can use the Pythagorean theorem to find the magnitude of the result. For some examples, see http://www.physicsclassroom.com/class/vectors/Lesson-1/Vector-Addition
Looks at the section entitled "The Pythagorean Theorem".