I know how I am supposed to solve this but I keep getting the wrong answer :/ May someone please help me? The picture is in the attachment below.

Question

anonymous · Answer

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anonymous · Answer

FYI please also post what answer you got as well as the correct answer.

anonymous · Answer

sinA = 12/13, sinB = -7/25, cosA = 12/5, cosB = -7/24

anonymous · Answer

I used cos(A - B) = cosAcosB + sinAsinB to solve, replacing all of the values above, into this equation

anonymous · Answer

I keep getting -0.958...

anonymous · Answer

I'm not sure what the correct answer is, I just know it's not the one I keep getting because it's being marked wrong :p

anonymous · Answer

When I plugged in the known values it looks like this
$$(12/13)*(-7/24) + (12/13)*(-7/24)$$

anonymous · Answer

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