6.8*16.8+19.3*3.2
＝6.8*16.8+（16.8+2.5）*3.2
＝6.8*16.8+16.8*3.2+2.5*3.2
＝16.8*(6.8+3.2)+2.5*4*0.8
=16.8*10+10*0.8
=168+8
=176