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In any textbook in Physics, you can find a Figure showing force decomposition on the sloped ramp.
    See, for example, this link:  http://www.dummies.com/education/science/physics/calculating-the-force-needed-to-move-an-object-up-a-slope/
From the figure,  F = W*sin(A),  where
     W is the weight, F is the tension force, and "A" is the inclination angle.
In your case  W = 325 kg (in your case kilograms are not the mass units - they are the force units, instead),  F = 275 kg.
So, sin(A) =  =  = 0.846.
Then  A = arcsin(0.846) = 1.008 radians = 57.8 degrees.