From the information provided, triangle 1 has three angles which are labelled,
34, 48 and 98 degrees. The unknown angle is 98 because angles in a triangle sum up to 180.
Triangle 2 has an angle labelled 34 and another one labelled a. If a is not 48 degrees, triangles 1 and 2 can still be similar because angle a in triangle 2 can take on several values (with 48 excluded). One of those values is 98, which would make the third angle in triangle 2 to be 48.
Hence the value of a that would refute Jennifer's claim is 98 degrees.