3 3/4*1 2/3+3 3/4*1/3=

3 3/4*1 2/3+3 3/4*1/3=15/4×5/3+15/3×1/3=15/4(5/3+1/3)=15/4×2=7,5

3 3/4*1 2/3+3 3/4*1/3=15/4*5/3+15/4*1/3=75/12+15/12=90/12=7,5