1. 83/13-2 5/13=83/13- (2×13+5)/13=(83-31)/13=52/13=4
2. 1 2/5 ÷4=(7×1)/(5×4)=7/20=0.35
3. (3.48+1.4-0.48)×2=4,4×2=8.8
4. 4×(2.2-3.6+1.8)=4×0.4=1.6
3/5×22/3=3/5×(2 · 3 + 2)/3=3/5×8/3=(3 · 8)/(5 · 3)=24/15=(8 · 3)/(5 · 3)=8/5=13/5 = 1.6
1.6-4=-2.4
2.7×10'2-0.3×10'3=2.7×100-3.0×1000=270-300=-30