9/20×5/21
=3/(4×7)
=3/28;
和7/25×15/14
=3/(5×2)
=3/10;
详细计算
很高兴为您解答,skyhunter002为您答疑解惑
如果本题有什么不明白可以追问,能不能再详细点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;