What is the mathematical relationship between the coeffcient and subscripts

Coefficients and subscripts are both numbers, instead of variables.
One can describe subscripts as numbers that describe something else
Coefficients are independent unless next to a variable or subscript

Ifound this on google “that means that the graph of a function with direct variation has these features: it is a straight line: because the slope is the ratio y/x = k. it passes through the origin (0,0): because y = kx = k (0) = 0.” i hope this you for what your looking for