Pet shop 2

Aneta has 13 chickens, 9 rabbits, 2 cats, and one dog. In the pet shop, 1 bird costs 100 CZK, 1 rabbit costs 120 CZK, 1 cat costs 400 CZK, and 1 dog costs 620 CZK.
1. How much did Aneta pay for all the animals in total?
2. Aneta bought all the animals at once. How much would she pay if she shopped during a sale when 30 CZK is deducted from her account for every 5th animal?

Correct answer:

a =  3800 Kc
b =  3650 Kc

Step-by-step explanation:

$a=13\cdot 100+9\cdot 120+2\cdot 400+1\cdot 620=3800\text{Kc}$

$$\begin{gathered} n=13+9+2+1=25 \\ b=a-30\cdot n/5=3800-30\cdot 25/5=3650\text{Kc} \end{gathered}$$

Try another example