Given:
mean = 64
standard deviation = 6
sample size = 50
Standard error of the sample mean = standard deviation / √sample size
Standard error = 6 / √50 = 6/7.07 = 0.85

let's find the value of added tax :
The value of added tax (VAT) = ₹ 3277.5
Here's the first part:
y = 8x - 9 --(i)
y = 4x - 1 -- (ii)
then in eqn( i),
4x - 1 = 8x -9 (from eqn( ii) )
-1 +9 = 8x -4x
8 = 4x
x =2
then in eqn (i),
y = 8*2 -9
= 16 -9
= 7
The 2nd part:
When these two equations are graphed, at point (2,7) the lines representing the two equations intersect because these values (2,7) satisfies the given equations.