Cream cheese costs £4.50 for 1kg.

Robbie buys 600 grams of cream cheese.

How much does he pay?

Answer: £2.70

Step-by-step explanation:

Recall:

1000g = 1kg

That is:

1000g of cream cost £4.50, then

1 g of cream will cost £4.50/1000

which means 1g cost £0.0045

Therefore:

600g of cream cheese will cost 600 x £0.0045

that is:

600g of cream cheese cost £2.70