Question

321:9::512:15::841:40::751:?
please answer it with solution

Answer 1

answer. is 42
3*2+1=9
5*1+2=15
8*4+1=40
7*5+1=42

so answer is 42

Answer 2

3*(2+1)=9
5*(1+2)=15
8*(4+1)=40
7*(5+1)=42