Give the step-by-step reasoning process and then the final answer. Mike wants to buy a new phone. The cost of the phone is $1300. How much more money does Mike need if he already has 40% of the amount he needs?
Mike already has 40 / 100 * 1300 = $520. This means he needs 1300 - 520 = $780 more, to buy the phone.
The final answer: 780.