21. since the annual salary is 40,000 and you are increasing to 56,000, what you need to find is 8% of what number is >= 16,000.
.08x >= 16,000
x >= 16000/.08
x >= 200,000
He needs at least 200,000 in sales to increase his income to 56,000 so 250,000 could be a possible solution.
22. 375 - .12x >= 15
-.12x >= 15 - 375
-.12x >= -360
x <= -360/-.12
x <= 3000
possible solution 2,500
23. 7x - 25 > 65
7x > 65 + 25
7x > 90
x > 90\7
x > 12.85
Since you can't have .85 of a person you have to round to 13 so
x > 13 Possible solution 15
