23 Luke invested £4000 in a savings account for 3 years.
Compound interest was paid at a rate of 1.8% each year.
Alexa also invested £4000 in a savings account for 3 years.
Simple interest was paid at a rate of 1.8% each year.
Luke got more interest than Alexa in total over the 3 years.
How much more?
You must show all your working.