Find the value of the each value in the parallelagram

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?

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

Find the value. a. 0.003 b. 0.03 c. 0.3 d. 3