The hard part is just making sense of what they are asking for.
4 times the quantity of a number decreased by one is just the expression:
4 * (x-1)
Where "x" is our mystery number.
Two more than the same number is just:
x + 2
Where "x" is our same mystery number.
They say that these two expressions are the same, so just set them equal to each other.
4*(x-1) = x+2
4x - 4 = x +2
3x -4 = 2
3x = 6
x = 2
The mystery number is 2. Plug in 2 and you will see that it works!
