In one semester, doug and Laura spent a combined 250 hours in the tutoring lab. If doug spent 40 more hours in the lab then Laura did how many hours did Laura spend in the lab

Step-by-step explanation:

What we have is a general equation that says this in words:

Laura's hours + Doug's hours = 250 total hours

Since we don't know either person's number of hours, AND since we can only have 1 unknown in a single equation, we need to write Laura's hours in terms of Doug's, or Doug's hours in terms of Laura's. We are told that Doug spent Laura's hours plus another 40 in the lab, so let's call Laura's hours "x". That makes Doug's hours "x + 40". Now we can write our general equation in terms of x:

x + x + 40 = 250 and

2x = 210 so

x = 105

Since Laura is x, she worked 105 hours in the lab and Doug worked 40 hours beyond what Laura worked. Doug worked 145. As long as those 2 numbers add up to 250, we did the job correctly. 105 + 145 = 250? I believe it does!