By what percent is a 100-watt light bulb brighter than a 60-watt light bulb? (Round percent to the nearest tenth.)

(100-60)/60 = ?

2400

To find the percent by which a 100-watt light bulb is brighter than a 60-watt light bulb, you need to calculate the difference in brightness first, and then express that difference as a percentage of the original value (60 watts).

Step 1: Calculate the difference in brightness.
100 watts - 60 watts = 40 watts

Step 2: Calculate the percentage by dividing the difference by the original value (60 watts), and then multiplying by 100 to convert it to a percentage.
(40 watts / 60 watts) * 100 = 66.7%

Therefore, a 100-watt light bulb is approximately 66.7% brighter than a 60-watt light bulb.