We were told that the homeowner whose house was assessed at $120,000 pays $1,800 in taxes. This means that the percent of the cost of the house chaged as tax is
1800/120000 * 100 = 1.5%
Since the rate is constant, then the amount of charge on a house assessed as
1.5/100 * 135000 = 2025
The tax on the house worth $135000 is $2025