So,
Based in the information, we could draw:
Let "x" be the length of the longer leg.
We could find the dimentions of the triangle using the Pythagorean theorem:

As you can see, we could solve this quadratic equation factoring:

Note that the solution x=0 has not any sense in the context of the problem.
Therefore, the appropiate value of x is 28.
Now, we have found that the length of the longer leg is 28cm.
The shorter leg of the right triangle is 7 cm shorter than the longer leg, so its value is 21cm.
The hypotenuse is 7 cm longer than the longer leg, so, the value of the measure of the hypotenuse is 35cm.