I think answer is E
If 2^x>75 then x>=7 since 2^6=64
In B: 2^x+3^x>1500
If x=6: 2^6=64 and 3^6=729 64*729 but 2^6<75
If x=7 2^7+3^7 must be >1500 and 2^7>75
Then is not sufficient
If B=50 (its almost the same as trying with 51 and much easier to calculate)
2^x > 30 not suff.
Agree. It has to be E.
Martin, Good job. The only thing I disagree with your solution is that it was never said that x was an integer in the question stem. So, we can say x starts at a value between 6 and 7.