Answer:
9 bottles of shampoo left.
Why?
Let x represent the number of bottles of shampoo that the shop has left.
Let f represent the number of bottles of shampoo Felix buys.
Let a represent the number of bottles of shampoo Anita buys.
This means that x = 30 - (f + a)
So, f = (2/5)*30
f = 12
So, a = (3/10)*30
a = 9
Plug it into our equation;
x = 30 - (f + a)
x = 30 - (12 + 9)
x = 30 - 21
x = 9
Therefore, the shop has 9 bottles of shampoo left.