Answer:
a) 
Step-by-step explanation:
Step(i):-
Given - 2 √3 + √75
we know that 25 × 3 = 75
- 2 √3 + √75
= -2 √3 + 
By using

= 
= 
= 
= 
The required plane Π contains the line
L: (-1,1,2)+t(7,6,2)
means that Π is perpendicular to the direction vector of the line L, namely
vl=<7,6,2>
It is also required that Π be perpendicular to the plane
Π 1 : 5y-7z+8=0
means that Π is also perpendicular to the normal vector of the given plane, vp=<0,5,-7>.
Thus the normal vector of the required plane, Π can be obtained by the cross product of vl and vp, or vl x vp:
i j k
7 6 2
0 5 -7
=<-42-10, 0+49, 35-0>
=<-52, 49, 35>
which is the normal vector of Π
Since Π has to contain the line, it must pass through the point (-1,1,2), so the equation of the plane is
Π : -52(x-(-1))+49(y-1)+35(z-2)=0
=>
Π : -52x+49y+35z = 171
Check that normal vector of plane is orthogonal to line direction vector
<-52,49,35>.<7,6,2>
=-364+294+70
=0 ok
*Please provide a picture of the table next time*
152+ 20n
n is the number of months
after 5 months
152+ 20(5)
=252
after 10 months
152+20(10)
= 352
Each time you need to find the balance for the certain month, replace the n with the number of months.
Hope that helped
The width is 13 ft I hope this helped you!