Number is n. n+85 = 3n-45. Add (45-n) to both sides getting 130 = 2n, ie., n = 65.

Let number be x

x  + 85 < 3x  - 45

130 < 2x

x > 65

Let the number be 'n'

Hence

85 + n = 3n - 45

2n = 130

n = 65

This is just plain English. Translating it into math does throw some people, but it's not hard.

"If 85 is added to a number" means "85 + x"

"the result is" means "="

"45 less than three times the number" means "3x - 45"

"what is the number" means "solve for x"

85 + x = 3x - 45

85 + 45 = 3x - x

130 = 2x

x = 65

x + 85 = 3x - 45

2x = 130

x = 65

The number is 65.

Let the number be x and so if x+85 = 3x-45 then the value of x = 65

Check: 65+85 = 150 and 3*(65) -45 = 150

x+85=3x-45

-x both sides

85=2x-45

+45 both sides

130=3x

divide both sides by 3

x=43.333r