Equation 1: ax+by=c equation 2: dx+ey=f a, b, c, d, e, and f are non-zero real numbers. which of the following could replace equation 1 and still have the same solution? select all that apply. a. a multiple of equation 1. b. the sum of equation 1 and equation 2 c. an equation that replaces only the coefficient of x with the sum of the coefficients of x in equation 1 and equation 2. d. an equation that replaces only the coefficient of y with the sum of the coefficients of y in equation 1 and equation 2. e. the sum of a multiple of equation 1 and equation 2.