The correct answer is: C. =SUM(A1:A5)/(10-10)
Excel will not be able to calculate this formula because the denominator is 0. When the denominator of a fraction is 0, the fraction is undefined.
In option A, =SUM(Sales)-A3, the denominator is not 0, so Excel will be able to calculate this formula.
In option B, =SUM(A1:A5)*.5, the denominator is not 0, so Excel will be able to calculate this formula.
In option D, =SUM(A1:A5)-10, the denominator is not 0, so Excel will be able to calculate this formula.