-3x + y - 2z = 10 |* -1
3x - y +2z = -10
5x -2y -2z = 12
--------------------------- I add these equations term by term
8x - 3y = 2
-3x + y - 2z =10 ⇒ -3x + y - 2z =10
x -y +z = 23 | *2 2x - 2y + 2z = 46
----------------------------- I add these eq.
-x -y = 56
8x - 3y = 2
-x -y = 56
this is the system after i reduce it ( it has only two variables x and y)
Answer:

Step-by-step explanation:
A proportion is an equation that defines that two ratios are equal. When the terms of a proportion are cross multiplied, the cross products are equal. Cross multiplication is the multiplication of the numerator of the first ratio by the denominator of the second ratio and the multiplication of the denominator of the first ratio by the numerator of the second ratio:

Therefore:

Yes, this is a function because the mapping is one to one. The domain is the the different inputs that can be put into the function, so the domain is {1,2,3,4,5}. The range is the different outputs the function can produce. So the range would be {40,80,120,160,200}.
Answer:
b
Step-by-step explanation:
distributive property-
-5c-(-20) which is -5c+20 which can also be 20-5c