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Work Shown:
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Extra info (optional section)
If you want to solve for h, then you could follow these steps.
9.80h+10 = 88.40
9.80h = 88.40-10 ... subtract 10 from both sides
9.80h = 78.40
h = 78.40/9.80 .... divide both sides by 9.80
h = 8
Valerie worked 8 hours on Friday.
As a check,
9.80h + 10 = 88.40
9.80*8 + 10 = 88.40
78.40 + 10 = 88.40
88.40 = 88.40
The answer is confirmed.