2+2=3
3+3=4
4+4=5
BUT....
5+5=10
10+10=20
SO...
what is 15+3?
P.S I don't know myself
Not sure but:
15+3=(3∗5)+3
Given that 3+3=4 thus 3=1
5+5=10 thus 5=5
Now substitute
1∗5+1=6
No... If 5 and 10 stay the same ... So does 15, and any other number that is not divisible by 5 becomes 1 so the answer is 16