9/20×5/21
=3/(4×7)
=3/28;
和7/25×15/14
=3/(5×2)
=3/10;
詳細(xì)計(jì)算
很高興為您解答,skyhunter002為您答疑解惑
如果本題有什么不明白可以追問(wèn),能不能再詳細(xì)點(diǎn)9/20×5/21=(3×3)/(4×5)×(5/3×7)=3/(4×7)=3/28;和7/25×15/14=(7/5×5)×(3×5/2×7)=3/(5×2)=3/10;