2 n/3 would be the closest answer although it looks as if the 2 is supposed to be multiplied by n/3 which would lead me to write it as 2(n/3)
It will be 3 cause 3 cubed is 27
Answer:
Plan A last 0.75 hours or 45 minutes.
Plan B last 1.5 hours or 90 minutes.
Step-by-step explanation:
Let
be the number of hours that the plan A last, an
the number of hours of plan B. Then for the Wednesday you have:

And for the Thursday is:

Multiply the equation of Wednesday by -3:

Using the method of addition using this last equation and the equation of Thursday

Replacing the value of
in one of the equations

Add up the sum and divide.
Practice Chart
1st Week: 6.25 Hours
2nd Week: 4.66 Hours
3rd Week: 15.33 - (1st Week + 2nd Week)
Solve:
6 1/4 + 4 2/3 = 10 8/12 or 10 2/3
15 1/3 - 10 2/3
14 4/3 - 10 2/3
4 2/3 hours practiced third week
Hope this helps!