Final answer:
Lindsay practiced guitar for 3 weekdays. Her practice time is represented by the equation 30x + 50 = 140, where x is the number of weekdays she practiced.
Step-by-step explanation:
The student's question requires solving a linear equation to determine how many weekdays Lindsay practiced guitar. First, we take into account the time Lindsay practiced on Saturday, which is 50 minutes. As she practiced for a total of 140 minutes last week, we subtracted the 50 minutes to find the remaining time practiced on weekdays. To express this as an equation, we let x represent the number of weekdays she practiced, knowing that she practices 30 minutes on each of those days. The equation is then 30x + 50 = 140.
By solving this equation, we isolate x:
30x = 140 - 50,
30x = 90,
x = 90 / 30,
x = 3.
Therefore, Lindsay practiced on 3 weekdays. This simple step-by-step calculation is an example of applying linear equations to solve real-world problems, specifically in the context of time management and practice schedules.