Let 'x' be the value of mirror with area bigger then 10 m^2.

Since value of mirror exceeding 10m^2 in area varies directly as the square of its area we can write:

400 = k*(60^2) where k is constant

k = 400 / 3600

k = 1/9

So the formula for calculating the value that varies directly as the square of the area would be

v = (1/9)* A^2 where v is value and A is the area of the mirror.

For A = 45 m^2 we get the following value

v = (1/9) * 45^2

v = $225

The price of 45 m^2 mirror is $225.