Question

递等式简便算法(13加5分之4)乘26分之5 12乘（4分之3减3分之二） 7分之3乘9分之5乘21

Answer 1

(13加5分之4)乘26分之5
=13x5/26+4/5x5/26
=5/2+2/13
=65/26+4/26
=69/26

12乘（4分之3减3分之二）
=12x3/4-12x2/3
=9-8
=1

7分之3乘9分之5乘21
=3/7x21x5/9
=9x5/9
=5

Answer 2

(13+4/5)*5/26
=13*5/26+4/5*5/26
=69/26
12*(3/4-2/3)
=12*3/4-12*2/3
=1

3/7*5/9*21
=5/21*21
=5