Answer:
Always
Step-by-step explanation:
a 'quadrilateral' is a 4-sided polygon and all 4-sides polygons have interior angles whose sum is 360 degrees
Mean=5
add the numbers given and divide it by the number of numbers given
the answer is B) 12a+6b
3+9=12 so 3a+9a=12a,
7-1=6 so 7b-(1)b=6b
x=-1, y=-3. (-1, -3).
x+y=-4
3x-6y=15
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x=-4-y
3(-4-y)-6y=15
-12-3y-6y=15
-12-9y=15
9y=-12-15
9y=-27
y=-27/9
y=-3
x+(-3)=-4
x-3=-4
x=-4+3
x=-1
