Graphing question and word problem

[vck710]

Hello everyone. Anything is appreciated and thank you in advance.

Determine the quadrant(s) in which (x,y) is located so that the given conditions are satisfied:

a) (x,-y) is in the second quadrant
b) (-x,y) is in the fourth quadrant


In a math class, 36 students took the final exam. If the average passing grade was 78, the average failing grade was 60, and the class average was 71, how many of these 36 students passed the final?

 

[arthur ohlsten]

a) if x.y is in 3rd quadrant then x,-y is in 2nd
check let x=-3 y=-2 then x=-3 -y= -[-2]

b)-x,y in 4th quadrant let -x= 2 then x=-2 let y=-3 then y=3
x,y is then -2,3 2nd quadrant

letr x fail and 36-x pass
36[71]=x[60]+[36-x]78 divide by 6
6[71]=10x+[36-x]13
426=10x+468-13x
3x=42
x=14
14 failed 22 passed

Arthur