During weekdays, Richard is working as a part-time library assistant at a university. He needs to work for a total of 30 hours a week. For the first three days of the week, he worked 21 hours. Complete the working equation that represents the number of hours, h, Richard needs to work to reach 30 hours for the week and solve the equation.

Answer 1

From the first three days, Richard has already worked for 21 hours, so he needs to work for an additional h hours to reach 30 hours for the week.

The working equation is:
21 + h = 30

To solve the equation, we can isolate h by subtracting 21 from both sides:

h = 30 - 21
h = <<9=9>>9

Therefore, Richard needs to work 9 more hours to reach a total of 30 hours for the week.