let the width of the uniform matte be x cm
We know the area of the picture is 60*40 or 2400 cm^2
The width of the whole frame would be 40+2x and the height would be 60+2x
since the area of the picture is equal to the area of the matte, the area of the whole thing is twice the area of the picture, so….
(40+2x)(60+2x) = 2(2400)
expand and solve that quadratic.
One of your answers will be extraneous, that is, it will make no sense for your picture. (hint: I got 10 cm for the width of the matte)
thank you SO much!!!! this helped me sooo much