Since they are simmilar we will then have the following relationships.

Now, we solve for x, as follows:

The expression goes along the lines of. 15 is to 10 what 9 is to x, with this as was done we solve for x and determine it's value, that since they keep proportionality.
Notice that you have a difference of cubes:

which can be factored using the rule,

So,

and just to make things look nicer, we can pull out 1/6 from the first factor and 1/36 from the second to get

Answer:
5*3*6 = 15*6 = 90
Step-by-step explanation:
C because it is a rhombis
The first poster is not an accurate representation of the painting, but the second poster is an accurate representation because the ratio between the first and original lengths did not equal the ratio between the first and original widths but the second poster's ratios were equal.