For every 10 dollars Ken earns mowing lawns, he gives 3 dollars to his younger brother,

For every 10 dollars Ken earns mowing lawns, he gives 3 dollars to his younger brother, Tim, who s him. Which of the following gives the relationship between d, the number of dollars Ken earns, and t, the number of dollars he gives to Tim. (From SAT of the day, Aug 8, answer d=10t/3) Why? And why not d=10/3t? Thank you so much Mike!