twice the difference between x and 28 is 3 times a number

[math_celebrity]

twice the difference between x and 28 is 3 times a number

The difference between x and 28:
x - 28

Twice the difference means we multiply x - 28 by 2:
2(x - 28)

The phrase a number means an arbitrary variable, let's call it x
x

3 times a number:
3x

The word is means equal to, so we set 2(x - 28) equal to 3x:
2(x - 28) = 3x