How can I solve 5+4 (x-6)=13

When 142 is added to a number the result is 64 more times the number my options are 35 37 39 41

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?

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17