Kenneth spent 10% of this earnings this week on a new joystick. If he is left with $405, how much were his earnings?
Step-by-step reasoning process below:
450
Since Kenneth spent 10%, then he is left with 100% - 10% = 90% of his earnings.

Since 90% of his earnings is worth $405, then 1% of his earnings is $405 / 90 = $4.

50.

Hence, Kenneth's earnings is $4.

50 x 100 = $450.

.

Final answer: 450