Giving a 150% salary raise would mean that your salary is going up by 150% meaning if you have a 10,000 salary, the raise would make it to where your salary is now going to be 15,000.
E.x ) Bill is getting a salary of $4,500 after working as a teacher. He received 150% salary raise this month.
Then his new salary = $4,500 + 150% of $4,500
Then Bill will get $11,250 as new salary.