There is little information please state more points.
Answer : y>0
f(x) = 9*2^x
f(x) is an exponential function

When we plug in positive value for x , the value of y is positive
When we plug in negative value for x , the value y is also positive
So for any value of x, the y value is positive always.
Range is the set of y values for which the function is defined
y values are positive , so range is y >0
Let's calculate the value of angle A and B
sin(A) =-4/5 → sin⁻¹(- 4/5) = A → A = - 53.13
cos(B) = -5/13 → cos⁻¹ (- 5/13) = B → B = 112.62
tan (A+B) = sin(A+B)/cos(A+B) with A+B = -53.13 + 112.62 = 59.49
tan (A+B) = sin(59.49)/cos(59.49) = 0.86154/0.507688 = 1.6969.
(Answer H = 56/33 = 1.6969)
The original price of the ring is <span>£</span>1400