Lindsay practices the guitar 50 minutes on Saturday and 30 minutes on most weekdays. Last week she practiced 140 minutes. How many weekdays did she practice? Write an equation in the form px+q=r to represent this problem
Let x be the number of weekdays that Lindsay practiced.
Since she practiced 30 minutes on most weekdays, she practiced 30x minutes in total on weekdays.
Therefore, Lindsay practiced 140-30x minutes in total.
Since she also practiced 50 minutes on Saturday,
the total time she practiced last week is 50+140-30x=190-30x minutes.
Thus, the equation representing this problem is 30x+50=190-30x. Answer: \boxed{30x+50=190-30x}.