Question 971476
Let the number be a,
Then, as per ques.
{{{5a-189=a/2}}}
=> {{{5a-a/2=189}}}
=> {{{9a/2=189}}}
=> {{{a=189*2/9}}}
=> {{{a=42}}} Ans. 

Check
42*5-189= 210-189 =21 =42/2.