I'm assuming you want us to solve for the unknown variable z

Combine like terms on the right side

Use the distributive property on the left side

Add both sides by 20 to cancel out the "-20" on the left side

Divide both sides by 10

That is the value of the known variable, z, in this equation. Let me know if you need any clarifications, thanks!
~ Padoru
The one on the right would be greater
Writing the equation that governs this situation:
-3C - (2.5C/hr)x = -18C
Simplifying, -3 - 2.5x = -18, or 3 + 2.5x = 18
Combining like terms: 2.5x = 18-3 = 15
Then x = 15/2.5 = 6. The temp. will reach -18C after 6 hours.
Answer: n = -3
Step-by-step explanation:
8(3n + 5) = -32
- <em>Divide both sides by 8.</em>
(3n + 5) = -4
- <em>Subtract 5 by both sides.</em>
3n = -4 - 5
3n = -9
- <em>Divide both sides by 3.</em>
n = -3