Can someone answer question 3b and 4 and provide an explanation.

Solve the system. -a+4b+2c=-8 3a+b-4c=9 b=-1 a.(0,11) ,-1,2) c.(1,1,-2) d.(2,-1,-1)

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?

What is 617.3 miles and each gallon of gas the car can travel 41 miles select a reasonable estimate of the number of gallons of gas karl used.