The apostrophe means take a derivative (basic Calculus).

A quick shortcut for a quotient of linear functions derivatives at a point is:

(ad - bc)/(cx-d)^2, where the quotient is (ax+b)/(cx+d).

You'd get (2 x 4 - 3 x (-5))/(3(2) + 4) = 23/10 = 2.3

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