Hello, you forgot to provide the systems of equation but upon searching for the origin of this problem, I found the two equations representing the situation:


In these two equations x represents the number of hours worked at the first job and y represents the hours worked at the second job. Since you worked 4 hours for the first job, you will just substitute 4 as the value of x. You can then solve for y to find the number of hours you worked at the second job.




The same value will actually result by plugging 4 for x in the second equation.
ANSWER: You and your friend worked for 6 hours at the second job.