Answer:
11.82%
Explanation:
We are given that
Cost to store A=4162
Cost to store=$155
Cost to store C=$160
Markup for store A=40%
Markup for store B=30%
Markup for store C=25%
Markup price=Cost price\times (100+markup)
Markup price for store A=
$226.80
Markup price for store B=
=$201.50
Markup price for store C=
$200
So, the best deal is store C.
If we purchased from store A then the price should be less than store C.
It means the price of store A should be less than $200 that is $199.99.
Discount=226.80-199.99=$26.81
Discount %=

Hence, the store A must offer discount 11.82% to buy the system there.