To find the number of hours Richard needs to work, we can set up the equation based on the total hours he needs to work (30 hours) and the hours he has already worked (2115 hours).
Let's first clarify the total hours worked in the first three days. From the format "2115," it looks like Richard has worked 21 hours and 15 minutes. We need to convert this to hours in decimal form:
21 hours and 15 minutes can be converted as follows:
- 15 minutes = 15/60 hours = 0.25 hours
- So, 21 hours and 15 minutes = 21 + 0.25 = 21.25 hours
Now we can write the equation:
\[ h + 21.25 = 30 \]
Now, we need to solve for \( h \):
- Subtract 21.25 from both sides to isolate \( h \):
\[ h = 30 - 21.25 \]
- Calculate the right side:
\[ h = 8.75 \]
So, Richard needs to work:
\[ h = 8.75 \text{ hours} \]
In conclusion:
Working equation:
\[ h + 21.25 = 30 \]
Solution:
\[ h = 8.75 \text{ hours} \]