Please explain how to calculate this question.

18. On 1 April 2015, the company rate of income tax changed from 35% to 30%. At the previous reporting date (30 June 2014) Monty Limited had the following tax balances: deferred tax assets $20 250 deferred tax liabilities $15 000. What is the impact of the tax rate change on income tax expense? *a. b. c. d. Increase $750 Decrease $750 Increase $875 Decrease $875