15.
Tom draws rectangles whose length are width are related. Lets say that given one of the sides, by multiplying this numer by a constant, we should get the other one. Let k be this constant . So, given a width of 2, we have a length of 3.6. An equation would be
[tex]2\cdot k\text{ = 3.6 }[/tex]So if we want to find the value of k, then
[tex]k\text{ = }\frac{3.6}{2}\text{ = 1.8}[/tex]So, by knowing the width, we multiply this number by 1.8 to get the length. So for a rectangle of a with of 3.5, we get
[tex]3.5\cdot\text{ 1.8 = 6.3}[/tex]So the length of the rectangle should be 6.3