Since sale is 40% so the price is 60%
61*(60%) = 36.6
the tax is 5%
so the price after tax is: 36.6 * (1 +5%) = $38.43
The answer
is ..................................b.3
Price elasticity is defined as

.
Here, the question has omitted to define variables, so we will ASSUME
p=price
x=variable,
and we're given
p+x^2-160=0
We calculate

by implicit differentiation with respect to p:
1+2x (dx/dp)=0
=>
E(x)=(dx/dp)=-1/(2x)
Therefore the price elasticity at x=65 is
E(65)=1/(2*65) =-1/130 (approximately -0.00769)