Answer:
44.4%
Step-by-step explanation:
The percentage change in a value is found using the formula ...
percentage change = ((new value) -(old value))/(old value) × 100%
With your numbers, this is ...
percentage change = (26 -18)/18 × 100%
= 8/18 × 100%
= 44.4444444...% . . . a repeating decimal
Rounded to tenths of a percent, the increase from 18 to 26 is about 44.4%.