(1+1/16+1/17+1/18)x(1/16+1/17+1/18+1/19)-(1+1/16+1/17+1/18+1/19)x(1/16+1/17+1/18)怎么算

问题描述:

(1+1/16+1/17+1/18)x(1/16+1/17+1/18+1/19)-(1+1/16+1/17+1/18+1/19)x(1/16+1/17+1/18)怎么算