A company's marginal cost function is C'(x) = 3 21/3.x + 64 and its fixed costs are 40, find the cost when 12 units are produced?

Can someone help me solve this business calc 1 problem? I have tried to use integration by substitution, but I am unsure what to do next after I get the integrated equation? Can you also explain what you do in each step of the solution? Thank you so much

A company's marginal cost function is C'(x) =321/3.x + 64and its fixedcosts are 40, find the cost when 12 units are produced?O42O74O50C92