Me with this i don't understand it !

X+ y = 5 ; x - y =3 solve using linear combination

Aline passes through the point (–7, 5) and has a slope of 1/2 which is another point that the line passes through?

In a small section of a stadium there are 40 spectators watching a game between the cook islands and fiji. they all support at least one of the two teams. 25 spectators support the cook islands and 16 of these support both teams. how many support only fiji?