michelle gets 70% on a 10-problem test, 80%on a 20 provlem test, 90% on a 30 problem test. if the three tests are combines into one 60 problem test, then what i

michelle gets 70% on a 10-problem test, 80%on a 20 provlem test, 90% on a 30 problem test. if the three tests are combines into one 60 problem test, then what is her overall percent