A percentage change can be calculated using ...
... percent change = ((new value) - (original value))/(original value) × 100%
Filling in the numbers gives
... percent change = ((88,200 - 105,000)/(105,000) × 100% = -0.16 × 100% = -16%
A negative number for a percentage change indicates a decrease.
The price of the house decreased by 16%.