2 19/40 is your answer without using a calculator

 First lets take whole number 5,3/8 =((8x5)+3)/8 = 43/8
Now take 2,9/10 = ((10x2)+9)/10 = 29/10
Now subtract 29/10 from 43/8
43/8 – 29/10
Take LCM
= ((43x5) -(29x4))/40
= (215 – 116)/40

= 99/40

40 ) 99 (2
       80
       19


so the answer is = 2,19/40