35*12+3500/70
= 35*12 + 50
= 35*(10+2) +50
= 35*10 +35*2 +50
= 350+70+50
= 470
（2.8+3.85/3.5）*4.6
= (2.8 + 1.1)*4.6
= 3.9 *4.6
= (4-0.1 )*3.6
= 4*3.6 -0.1*3.6
= 14.4 - 0.36
= 14.04