Answer:
15 cm
Explanation:
If we have two sides of a parallelogram in the ratio 5:4, then the other two sides must also be in the same ratio.
If the perimeter is 54, we can create the following equation regarding the length of each side
![5x+4x+5x+4x=54\\\\18x=54\\\\x=3](https://img.qammunity.org/2021/formulas/mathematics/middle-school/q404myiayvvuedt755q0uj1vf2cusnqtcq.png)
As our value for x is 3, and we know that the value for the larger side is 5x, we can simply plug in x to get the length of the larger side
![5x\\\\5(3)\\\\15](https://img.qammunity.org/2021/formulas/mathematics/middle-school/w8b8agz04ym7uzedisosydqyiwbaynzdvs.png)