√z = 13 - 8
√z = 5
z = 5²
z = 25
In this case the z can be any number, however z cannot be less than 0 and that is the restriction. (for example; √-1 = irrational number, cannot be solved.)
15 sandwiches
3 tomatoes= 5 sandwiches.
So if there's 9, that makes 3 groups of 3 tomatoes which would make 3x5 or 5+5+5 ;-;
15.