let a, b be Element of multEX_0; :: thesis: ( a <> 0. multEX_0 implies ex x being Element of multEX_0 st x * a = b )
assume A1: a <> 0. multEX_0 ; :: thesis: ex x being Element of multEX_0 st x * a = b
reconsider p = a, q = b as Element of REAL ;
reconsider x = q / p as Element of multEX_0 ;
p * (q / p) = q by A1, XCMPLX_1:87;
then x * a = b by BINOP_2:def 11;
hence ex x being Element of multEX_0 st x * a = b ; :: thesis: verum