ANSWER:
The bare canvas is of 17 cm length.
SOLUTION:
Given, a square-shaped canvas painting was enlarged by adding a 4-centimeter wide decorative frame to the length and width of the canvas.
The area of the framed painting is 625
,
Let, the length of the bare paintings be x.
Then, after adding the frame,
length becomes x + 4 + 4 = x + 8. [we added 4 two times, because frame adds on both sides of painting.]
Now, we are given that, area of the framed painting is 625

Area = 625
= 625
=

x + 8 = 25
x = 25 – 8 = 17
Hence, the bare canvas is of 17 cm length.