please help on the ones that are boxed.

for the first box: For substitution you plug in the equations to solve for the variable, while elimination cancels out variables, and graphing displays the solutions on your calculator.
for the second box: I'd say that For the three methods you are solving to figure out what x or y is. The value of x and y means that when you plug in the numbers you got for x and y into the equation, the equation is equal.