Easy question for smart people but i’m not smart, question in photo

If your annual gross income is $62,000 and you have one monthly car payment of $335 and a monthly student loan payment of $225, what is the maximum house payment you can afford. consider a standard 28% front-end ratio and a 36% back-end ratio. also, to complete your calculation, the annual property tax will be $3,600 and the annual homeowner's premium will be $360.

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?