Please I really need help- A student found the quotient of 5×10^-5 and 3.5×10^-3 to be 8.5×10^-9. What is the error? What is the correct product?

Ahigh definition tv cost $800 with a down payment of 2/5 of the cost. how much is left to pay, in dollars after the down payment has been made?

Adifferent website gives the cost for the first train as £56.88 and the second train as £20.11 with a £9.50 charge for cycle storage for the whole trip. how much would the journey cost you?

10% of 1,900,000. show me how you got the answer