For this example, we must combine not permutate; this because a salad in which you first use apple then tomato is the same as the one in which you use first tomato then apple, so order does not matter.
Me must do "10 combine 7" which is written by the binomial coefficient
; in general a binomial coefficient is written by:
In which
and 
are positive integers, such that 
.
So, for this problem:
Hence, there are 120 different ways to make the fruit salad.
Me must do "10 combine 7" which is written by the binomial coefficient
In which
So, for this problem:
Hence, there are 120 different ways to make the fruit salad.