Which calculations preserve direct proportion in their stated contexts? Select all that apply.
Four identical tiles cover 1.2 square metres, so ten cover 3 square metres.✓Correct answer
Five badges cost 10.50.
Three litres of paint cover 24 square metres, so seven litres cover 56 square metres.✓Correct answer
Six identical folders weigh 1.8 kilograms, so twelve weigh 2.4 kilograms.
Explanation
Four tiles covering 1.2 square metres gives 0.3 square metres per tile, so ten cover 3 square metres; three litres covering 24 square metres gives 8 square metres per litre, so seven cover 56. The folder claim is especially tempting, but doubling the number of identical folders must double 1.8 kilograms to 3.6 kilograms, not merely add 0.6 kilograms.