(-5,-10)E
(-5,-3)F
(-3,-10)G
1. we know she needs 3 packs of biscuits
2. Shop A you only need to pay for 2 packs
3. Shop B you only need to pay for 2 packs
4. Shop C you need to pay for all three
5. so we know C is out of the option.

so shop A and B will cost the least
[(21 + 6) − 3^2] ÷ 9 ⋅ 2=[(27) − 9] ÷ 9 ⋅ 2
=18 ÷ 9 ⋅ 2
= 2 . 2
= 4