Somebody pleaseee help me

If 10 men take 18 days to mow 60 acres of grass, how long will 15 men take to mow 80 acres?

Is it greater than or less than7*3_9*2

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236