Declan invested $12,000 at a simple interest rate of 4.75% for 3 years. How much interest did he earn?

The interest earned can be calculated using the formula: interest = principal * rate * time.

The principal (P) is $12,000.
The rate (R) is 4.75% expressed as 0.0475.
The time (T) is 3 years.

Thus, interest = $12,000 * 0.0475 * 3 = $1,710.