What is the best estimate of 2/5 + 1/7 in a equation

Which function has the same domain as y=2x

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

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?