Please help with question 5 I’m confused

Harry owes the bank money. to repay his debt, he paid $150 back to the bank each month. after 10 months, his remaining debt was $6900. what was the original amount of harry's debt? how long did it take harry to pay back his entire debt?

Apudding recipe requires 2/3 of a cup of milk for every 1 3/4 cups of sugar. what is the unit rate of sugar to milk in the pudding recipe?

For which of these functions is function composition commutative with ƒ(x) = (x + 1 /3x − 2) ? a - g(x) = (3x − 2/x + 1)b - g(x) = (3x − 3/x + 2)c - g(x) = (2x + 1/3x − 1)d - g(x) = (2x − 1/3x + 1)