question: Jerry is twice as old as he was 5 years ago. How old will Jerry be in 3 years?
answer: We know that Jerry's Age/2 = Jerry's Age - 5
  Therefore Jerry's Age = 2 Jerry's age - 10
  Therefore -Jerry's Age = - 10
  Therefore Jerry's Age = <<10=10>>10
  In three years Jerry will be 13 because 10 + 3 = <<10+3=13>>13
  #### 13