Answer:
(x-5)(x-6)= 20
x²-6x-5x+30=20
x²-11x+30-20=0
x²-11x+10=0
b²-4ac =(-11)²-4(1*10)= 81
Δ is strictly positive, the equation x²−11x+10=0 admits two solutions.
(-b-√Δ)/2a =(11-9)/2 =1
(-b+√Δ)/2a=(11+9)/2=10
solution (1,10)
x= 10inches
original image area: 10²=100inches