App Designer: Setting up equations, properties vs. callbacks?

New to app designer. Trying to figure out how I should format the following equations and whether I should insert them as properties or callback functions.

For the one in this image: Looking for f which will have many answers, and have the answer go to a field edit (numeric) box. p, q, and r will have values as shown in the table below going to (4,4,4) L, W, and H are the dimensions of the room being modeled which are entered by the user to field edit (numeric) boxes. c is the speed of sound as derived from this equation: c = 331.4 + 0.6T + 0.0124H in m/s c = 3.28084(331.4 + 0.6T + 0.0124H) in ft/s Where T is temperature in Celsius and H is the humidity in % entered by the user in a edit field (numeric) boxes. c will also be sent to an edit field box once calculated.

Additionally, the Reverb Time equation (RT) RT = 0.049 · V / A when measured in feet RT = 0.161 · V / A when measured in meters

Where V is volume of the room calculated by V = L*W*H And A is the equivalent absorption, A will also be sent to a edit field box A = α1×S1 + α2×S2 + α3×S3 + α4×S4 + α5×S5 + α6×S6 Where αn and Sn correspond to values in edit field boxes

Attached is the app I am working on.