Which pair is correct to fill in the blanks？

Tom has 10 candies and Mike has 7 candies. If you want to know the sum of candies Tom and Mike have, the process called ( 1 ) is necessary. If you want to know the difference, the process called ( 2 ) is necessary.

1- addition / 2- multiplication 1- addition / 2- subtraction 1- subtraction / 2- addition 1- subtraction / 2- division