To answer this, you need to put 115 and 345 into a fraction.
115/345
Reduce it, which results in the fraction 1/3.
Now you have to convert 1/3 to a decimal: .33333
The 3 will continue to repeat. To convert a decimal to a percent you simply need to move the decimal point two places to the right: 33.333
Simplified, your final answer (with a fraction) is 33 1/3%
Or rounded to the nearest tenth of a percent, 33.3%