Math Help - Finding the arithmetic mean

1. Finding the arithmetic mean

If we have five numbers :X,Y,Z,L,k,the arithmetic mean between X,Y,Z is equal to 8,and the arithmetic mean between X,Y,Z,L,K is equal to 7,what is the arithmetic mean between L,K?

2. Re: Finding the arithmetic mean

$\frac{X+Y+Z}{3}=8$

$\frac{X+Y+X+L+K}{5}=7$

3. Re: Finding the arithmetic mean

So the answer is 5,5?

4. Re: Finding the arithmetic mean

I would write 5.5 but yes, 5,5 in France and elsewhere I believe..