Two students are discussing the use of a trial balance. They wonder whether the following errors, each considered separately, would prevent the trial balance from balancing.

  (a) The bookkeeper debited Cash for $600 and credited Salaries and Wages Expense for $600 for payment of wages.
  (b) Cash collected on account was debited to Cash for $900 and Service Revenue was credited for $90.
What would you tell them?