168.1/(4.3*2-0.4) [16分之9-(8分之5-12分之7)]*25分之24
1个回答

168.1/(4.3*2-0.4)

=168.1÷(8.2)

=20.5;

[16分之9-(8分之5-12分之7)]*25分之24

=(9/16-10/16+7/12)×(24/25)

=25/48×(24/25)

=1/2;

7分之5+25分之19*4+25分之21*19

=5/7+(19/25)(4+21)

=5/7+19

=19又7分之5;

2分之1/[5-(2分之1+3分之1)*2.4]

=(1/2)/(5-1.2-0.8)

=1/2/3

=1/6;

求未知数X的值

X分之6.5=13:14;

13x=14×6.5;

x=7;

4分之3X=20分之1X+17.5

15x/20-x/20=17.5;

14x/20=17.5;

x=25;