CONCEPT: The question tests on the abilities to frame and solve algebraic equations.
SOLUTIONS:
Let D = the number of Democrat senators last year
Then D + 20 = the number of Republican senators last year,
As the total members remain same;
The number of Democrat senators this year
=D+2 (These are the 2 Republican Members who turned Democratic)
Thus, the number of Republican senators this year
= Number of Republican senators last year + 2
(D + 20) - 2
= D + 18 (The two members have been moved from Republic to Democrat)
Total Senate Members this year
= Republic + Democrat
= (D+18) + (D+2) = 2D+20
Thus according to question,
(D + 18) [Republic Members this year]
= (2/3) (2D+20) [Total Senators this year]
3(D + 18) = 2(2D + 20)
3D + 54 = 4D + 40
14 = D
Therefore, the total number of senators this year is 2(14) + 20 = 48.(Option E)