Derek must choose a four digit PIN number. Each digit can be chosen from 0-9. How many different pins can Derek choose?

Can someone me with this problem . show your work .

Jenny earned a 77 on her most recent test jenny score is no less then 5 points greater then 4/5 of terrance’s score if t represents terrance score which inequality represents the situation

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.