Answer:

280 is the correct answer..

x=101/65, y=-16/65. (101/65, -16/65).

Step-by-step explanation:

4x+9y=4

9x+4y=13

9(4x+9y)=9(4)

-4(9x+4y)=-4(13)

36x+81y=36

-36x-16y=-52

65y=-16

y=-16/65

4x+9(-16/65)=4

4x-144/65=4

4x=4+144/65

4x=404/65

x=(404/65)/4=101/65

x=101/65, y=-16/65.