Oque significa a letra e depois de números grandes?

What is the measure of ac? 5 units 13 units 26 units 39 units

Which of the following is correct interpretation of the expression -4+13

Find the equation of the ellipse with the following properties. the ellipse with foci at (0, 6) and (0, -6); y-intercepts (0, 8) and (0, -8).edit: the answer is x^2 over 28 + y^2 over 64 = 1