James bought 2 bottles of lemonade and 1 bag of crisps for £1.40 . jill bought 1 bottle of lemonade and 3 bags of crisps for £1.70 how much is a bottle of lemonade? how much is a bag of crisps?

Hence
2L + C = 1.4
-2L - 6C = -3.4
Add (This will eliminate 'L' )

-5C = -2.0
5C = 2.0
C = 0.4 = £0.40p

2L + 0.4 = 1.40
2L = 1.40 - 0.40 = 1.00
L = 0.50 = £0.50p.

Hence a lemonade (L) costs £0.50p & a Crisps (C) costs £0.40p.

The surface area would be 576 because you multiply all the numbers then multiply that number by 6