1.85*42+11.5*4.2=18.5*4.2+11.5*4.2=(18.5+11.5)*4.2=30*4.2=126
=1.85×42+1.15×42=（1.85+1.15）×42
1.85×42+11.5×4.2=1.85×42+1.15×42=（1.85+1.15）×42=3×42=126
