- #1

songoku

- 2,336

- 337

## Homework Statement

The number of ways to choose a pair of distinct numbers a and b from the set {1, 2, 3, ...49} such that |a - b| ≤ 3 is

a. 141

b. 144

c. 147

d. 150

e. none of the above

## Homework Equations

not sure

## The Attempt at a Solution

Is a = 41 and b = 42 considered the same as a = 42 or b = 41? Or they are two different cases?

Thanks