19+3分之2乘20+3分之1越详细越好

问题描述:

19+3分之2乘20+3分之1
越详细越好

(19+2/3)*(20+1/3)
=(57+2)/3-(60+1)/3
=-2/3

19+3分之2乘20+3分之1
=(20-1/3)*(20+1/3)
=20^2-(1/3)^2
=400-1/9
=399又9分之8