Question

What's 17= z- (-9) days

Answer 1

z - (-9) is the same as z + 9. Subtracting a negative is the same as adding.

Therefore
17 = z - (-9)
is the same as
17 = z + 9

To get 'z' all by itself, we need to subtract 9 from both sides. We subtract 9 from both sides to undo the "plus 9" occurring to the 'z' on the right side.

17 = z + 9
17-9 = z + 9=9 ... subtracting 9 from both sides
8 = z
z = 8

So the answer is z = 8

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Check:

17 = z - (-9)
17 = 8 - (-9) ... replace z with 8
17 = 8 + 9
17 = 17
Answer checks out

Answer 2

The calculated value of z in the equation 17 = z - (-9) is 8

How to determine the value of z in the equation

From the question, we have the following parameters that can be used in our computation:

17 = z - (-9)

When the bracket is evaluated, we have

17 = z + 9

So, we have

z = 17 - 9

Evaluate

z = 8

Hence, the value of z in the equation is 8