(330-250)/250 -1= 32% can someone explain to me how we get that answer

If you have just (330-250) / 250, your answer is .32, which is 32%.

If you have (330-250) / 250 -1, your answer is -.68, which is -68%.

If you have 330/250 - 1, your answer will be 32%.

You can't get 32% fom the problem given.