Answer: plan A lasts for 0.5 hour. Plan B lasts for 0.75 hour.
Step-by-step explanation:
Let x represent the duration of plan A.
Let y represent the duration of plan B.
On Friday there were 3 clients who did plan A and 2 who did Plan B.
Joe trained his Friday clients for a total of 3. It means that
3x + 2y = 3- - - - - - - - - -1
On Saturday there were 5 clients who did plan A and 6 who did plan B. Joe trained his Saturday clients for a total of 7 hours. It means that
5x + 6y = 7- - - - - - - - - 2
Multiplying equation 1 by 5 and equation 2 by 3, it becomes
15x + 10y = 15
15x + 18y = 21
Subtracting, it becomes
- 8y = - 6
y = - 6/-8
y = 0.75
Substituting y = 0.75 into equation 1, it becomes
3x + 2 × 0.75 = 3
3x + 1.5 = 3
3x = 3 - 1.5 = 1.5
x = 1.5/3
x = 0.5
