express -3/5 as a rational number with denominator:

20

-30

35

-40

the given fraction is .

1. 

if denominator is 20.

20/5 = 4 i.e. denominator is multiplied by 4.

so we must multiply numerator also by 4.

thus

2.

if denominator is -30.

30/5 = 6 i.e. denominator is multiplied by 6.

so we must multiply numerator also by 6.

thus  

3.

if denominator is 35

35/5 =7

4.

if denominator is -40

40/5 =8

hope this helps you.

cheers!!