简便运算!7分之5×22-7分之5

问题描述:

简便运算!7分之5×22-7分之5

原式=(22-1)x5/7
=(21)x5/7
=3x5
=15

7分之5×22-7分之5
=5/7x(22-1)
=5/7x21
=105/7

22*5/7-5/7
=(22-1)5/7
=15