This lesson explains how to use a variable to solve for a missing number in an equation involving a single operation, how to choose the operation needed to solve for the variable in a one-step equation, and how to match a realistic situation to an equation, expression, inequality, table, or graph and solve for a missing variable. An optional hands-on activity that explains the number sentence is also included.
...a presentation with 3 speakers who each speak 10 minutes equals the 30 minutes allotted. So, we know that we are starting with a balanced equation:
3 speakers • 10 minutes = 30 minutes
With only 2 speakers, the number of minutes that each speaker uses must change but still equal 30 minutes. So, we change the number of minutes to a variable (since this is the part of the equation that must change) and we change 3 speakers to 2 speakers.
2 speakers • N minutes = 30 minutes
To isolate N, we need to ...