Please Solve

Question

1. Each of the following refers to two quantities. Introduce a variable to represent the first of these quantities, and then represent the second quantity in terms of the same variable.

 

A number;  the number obtained by adding 15 to the original number
A number; three less than twice the number
A number; the product of the number and two less than the number
Demochares' age; one fifth of his age
The number of minutes it takes Alphonse can do a job; how much-what portion-of the job Alphonse can do in one minute.

Answer 1

n; n+15

n; 2n-3

n; n(n-2)

n; n/5

n; 1/n