One saturday morning serena left her house walking at a rate of 2 1/2 miles per hour. one hour later jackson left their house following the same route jogging at 4 miles per hour. how long will it take jackson to catch up to serena?

Eric and shiloh each have a savings account. the ratio of eric’s account balance to shiloh’s account balance is 4: 3. together they have a total of $140 in their accounts. use the tape diagram below to you determine the balance of eric’s account.

Me with these questions , i don’t understand scientific notation!

Find two numbers if their ratio is 4: 7 and their difference is 123.