Sharon earns $25 per item. This means that this number is increasing with each item sold, then you will have a variable with this number, such as 'x'.
Plus a base salary of $100 per week. This means that this number is always true for each week and will not change when looking at a weekly perspective.
How many items must she sell to earn at least $700 per week. This is the end goal or even slightly over $700.
To set it up:
25x + 100 ≥ 700
To solve:
25 x + 100 ≥ 700
- 100 -100
______________
25x ≥ 600
___ ___
25 25
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x ≥ 24
Interpret:
Sharon must sell at least 24 items.