one to increased costs the labour charge of a certain establishment from $1.20 to $1.40 per hour .what is the percentage increase.

(1.4-1.2)/1.2 = .2/1.2 = 1/6 = 16.6%

To find the percentage increase in labor charges, you can use the following formula:

Percentage Increase = ((New Value - Old Value) / Old Value) * 100

In this case, the old value of labor charge per hour is $1.20 and the new value is $1.40. Let's plug those values into the formula:

((1.40 - 1.20) / 1.20) * 100

Simplifying this equation, we get:

(0.20 / 1.20) * 100
(1/6) * 100
16.67%

Therefore, the labor charge has increased by approximately 16.67%.