Question about changing magnetic flux

[Dany7777777]

Homework Statement

A 200-loop coil of cross sectional area 8.5 cm2 lies in the plane of the page. An external magnetic field of 0.060 T is directed out of the plane of the page. The external field decreases to 0.020 T in 12 milliseconds.
What is the magnitude of the change in the external magnetic flux enclosed by the coil?

Homework Equations

$\Phi$m = A * B

The Attempt at a Solution

Ive tried solving for both values of magnetic flux at each time and finding their difference. However, I still seem to get it wrong. I don't know If I am missing something, any help or tips would be greatly appreciated.

 

[bdh2991]

i believe it would just be the initial flux - the final flux...

the full equation you want is $\Phi$= N*B*A*cos($\phi$)
(N = the number of turns of the coil)

however the direction of the area and the magnetic field are the same so cos(phi) = 1
just convert 8.5 cm² to m² which is 8.5 * 10^-4

so... N(.06T)(A) - N(.02T)(A), just plug in your numbers...i believe this is right anyway, someone should check my work