二步方程 三題

1.3又4/5+9/k=18

3又4/5+9/k-3又4/5=18-3又4/5

9/k=14又1/5

9/k/9=(14又1/5)/9

(9/k)*(1/9)=(71/5)*(1/9)

k=71/45

k=1又26/45


2.36-17.2/c=18

36-17.2/c-36=18-36

-17.2/c=-18

18=17.2/c

18*1/17.2=17.2/c*1/17.2

18/17.2=c

c=1又1.8/17.2

c=1又9/86


3.15.2-140/a=13又4/5

15.2-140/a+140/a=13又4/5+140/a

15.2=69/5+140/a

15.2-69/5=69/5+140/a-69/5

76/5-69/5=140/a

7/5=140/a

7/5*1/140=140/a*1/140

7/700=1/a

100=1/a

100*1/1=1/a*1/1

100=a

a=100

1.
3又4/5+9/k=18
3又4/5+9/k-3又4/5=18-3又4/5
9/k=14又5/1
9/k=71/5
9/k*1/9=71/5*1/9
k=71/45
k=1又5/9

2.
36-17.2/c=18
36-17.2/c+17.2/c=18+17.2/c
36=18+17.2/c
36-18=18+17.2/c-18
18=17.2/c
18*1/17.2=17.2/c*1/17.2
18/17.2=c
1又2/43=c
c=1又2/43

3.
15.2-140/a=13又4/5
15.2-140/a+140/a=13又4/5+140/a
15.2=13又4/5+140/a
15.2-13又4/5=13又4/5+140/a-13又4/5
1又2/5=140/a
7/5=140/a
7/5*1/140=140/a*1/140
1/100=a
a=1/100