Answer:
They fall into 
 tax bracket.
Explanation:
We need to calculate their tax return jointly, which tax bracket will they fall into.
Given :-
A taxpayer had a taxable income of $42,700, and his spouse had a taxable income of $48,100.
If they wish to file their tax return jointly then

In married filling jointly table
The combine salary 
 lies between 
 
so, the tax bracket is 

Therefore, they fall into 
 tax bracket.