The fraction of the amount of money that Jing had left is  

The fraction of the amount of money Jing spent on the PACK of pens =  

The fraction of the amount of money she spent on a pack of marker =  

The fraction of the amount of money she spent on a pack of pencils =  

The fraction of the money left = 1

Further Explanation

One way to determine the total fraction of the amount of money she spent  = the fraction of the money left - the fraction of the amount she spent on pack of pens + fraction of the amount spent on marker + fraction of the money she spent on pencils

Firstly, WITHOUT the fraction of the money left, we have:

=  +  +  

=  +  + , it ALSO the same as

= (8+12+3) / 24 (24 is the lowest common denominator)

=  

Since the fraction of the money left = 1

Therefore we have:

= 1 –  

= (24 x 1) – (23 x 1) / 24 (24 is the smallest number that can divide the denominators)

Therefore we have:

= 24 – 23 / 24

= .

Therefore the fraction of the amount that Jing has left is .

Notably, we solve this question using the BODMAS rule.