Sorry The answer is 143547 . Let me explain
first example given in the question which is
5+3+2= 151022
Let 5=a
3=b
2=c
Now, the pattern for the answer on the RHS is:
First two digits= a×b
Next two digits= a×c
Last two digits= [(a×b)+(a×c)]-b
Accordingly, applying the same to 7+2+5 we will get:
First two digits= 7×2=14
Next two digits= 7×5=35
Last two digits= 14+35-2=47
Thus, 7+2+5= 143547