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Change of values

If you know the starting value and the change (how much was added or taken away), the result is found by addition: start+Δ\text{start}+\Delta. A positive change increases the value; a negative change decreases it.
result=start+Δ\text{result}=\text{start}+\Delta
Δ>0\Delta>0 — increase; Δ<0\Delta<0 — decrease
On the number line: move from start by Δ|\Delta| in the sign’s direction
Start + change
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