Write the expanded form of the expression.
-1/2 (y - x) = ?

Matt and brian were solving a system of equations. they both noticed that the two lines had the same slope. brian said that because each line in the system had the same slope, the two lines had to be parallel, which meant the solution to the system was "no solution" matt disagreed, and said they should also look at the y-intercepts before determining how many solutions there were. who is correct?

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

How do i do this activity, is appreciated