Answer:
24 cm
Step-by-step explanation:
For square's to be congruent they must be exactly the same. Also, since squares must have 4 equal sides, both the length and width of the canvas must be divided by the same number in order to give us the longest side. Therefore, since the smallest number we can divide both the width and length by is 2 we are left with 4 equal squares with a size of 18 x 24. Therefore, the longest side length would be 24 cm.
