Question

2/1 X 3/1 +12/5 X 2/1 5/4 X7/5 -2/1 （6+15/2）X5

Answer 1

二分之一写作1/2

1/2x1/3+5/12x1/2

=1/6+5/24

=4/24+5/24

=9/24

=3/8

4/5x5/7-1/2

=4/7-1/2

=8/14-7/14

=1/14

(6+2/15)x5

=6x5+2/15x5

=30+2/3

=30又2/3