Um....
Okay, we know that the model plane is 48 times smaller than the actual plane which means that the actual plane is 48 times bigger. To be able to solve this problem, there are 2 ways to do it.
First way, 28×48=1344 inches long
Second way, 28÷1/48 is also equal to 1344 inches long. Ad a result, the actual length is 1344 inches long. Hope it help!