GCSE Maths Practice: direct-proportion

\( \begin{array}{l}\text{Which of these situations show direct proportion?}\end{array} \)

Select all correct options:

\( \text{Doubling the number of machines doubles production.} \) \( \text{Tripling distance triples travel time (at constant speed).} \) \( \text{A worker earns £72 in 6 hours and £108 in 9 hours.} \) \( \text{The weight of a cake remains the same regardless of ingredients.} \)