The first bubble is the answer
x + 1 = x + 1
x - x = 1 - 1
0 = 0
So you subtitute y=3x into
2x+y=15
so
2x+(3x)=15
add like terms
5x=15
divide both sides by 5
x=3
subtitute x=3 into first equation (y=3x)
y=3(3)
y=9
When two variables are inversely proportional the relation between them can be written as:

Here, k is the constant of proportionality and is always equal to the product of the two variables. So using the given values of z and x, we can find k first.

The constant of proportionality for the given inverse proportion comes out to be 2. Using the value of k in the equation, we get:

We have to find the value of z when x=28. So replacing x by 28, we get:

Thus, rounding of to nearest thousand the value of z comes out to be 0.071 if x is equal to 28.