Answer:
Let's assume that the total battery capacity is represented by 1 unit.
According to the information given, you use 3/4 (or 6/8) of your battery while video chatting. Additionally, for every 2/5 (or 4/10) of an hour, you use 1/8 of the battery.
Let's denote the time you video chatted as "t" in hours.
The amount of battery used during video chatting can be represented as (6/8) of the total battery capacity.
The amount of battery used for the given time can be represented as (1/8) multiplied by the number of intervals of (4/10) hours, which is (4/10)t.
Setting up the equation:
(6/8) = (1/8) * (4/10)t
Simplifying:
6/8 = 4/80 * t
6/8 = 1/20 * t
To solve for t, we can multiply both sides of the equation by 20/1.
(6/8) * (20/1) = t
(3/4) * (20) = t
15 = t
Therefore, you have video chatted for 15 hours.