A(Sqd) + B(Sqd) = SQR RT of C(Sqd) x 2

Geometric Dimensioning and Tolerancing is a matter of Geometry, not Algebra. It helps to bear in mind which geometry the notations refer to. The feature control frames refer to features, not dimensions per se. The formula you refer to, I think, is Pythagorean Theorem, that is C=Sqrt of (A-sq + B-sq), which can be used to find the distance between two points in a plane. The formula you typed is similar but not mathematically equivalent to Pythagorean Theorem.

The times 2 factor which I am thinking of is when people try to find the tolerance on a distance where both ends of the dimension are covered by a tolerance on the position of the endpoint. Both ends can be further apart by the tolerance, or both ends can be closer together by the tolerance. In that way, the distance between can vary by the sum of the positional tolerance of both ends, and if both ends have equivalent tolerances, the distance tolerance is

__2 times__ the position tolerance of one end. In your drawing, the tolerance on dimensions 5 and 9 is given directly, and not determined by positional tolerance of the endpoints.

The supplier’s engineer points out lack of a diameter symbol in the tolerance of position feature control frame. Yet, the

__centerline__ of a hole is the feature controlled by a tolerance of position on a cylindrical feature (and I include an oval-shaped hole as a cylindrical feature). The tolerance of position on a centerline is interpreted as a diameter. There are different editions of the Y14.5 GD&T standard. I can't remember if all of them require the diameter symbol. If the diameter symbol does not explicitly appear, I can’t think of another interpretation which makes sense for this geometry.

Dimensions associated with balloons 10 and 11 also have bonus tolerance, indicated by the circled-M inside the feature control frame. Bonus tolerance is a more complicated explanation, that should be understood by the persons who machine or measure this part geometry.