Please help me with this #5

Which ratio is equivalent to 10: 85

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

Study results indicate that the mean length of time people spend on a bus in a city is between 21.2 min and 24.5 min what is the study margin of the error?