please solve 6 number

Answer:
5
Step-by-step explanation:
The mean is calculated as
mean = [tex]\frac{sum}{count}[/tex]
Here sum = 75, mean = 15 and let n be count, thus
[tex]\frac{75}{n}[/tex] = 15 ( multiply both sides by n )
75 = 15n ( divide both sides by 15 )
5 = n ← number of terms