15/35 as a percentage is 42.86%. This number tells you that the fraction is a little less than half of a whole.
If you reduce the fraction first, 15/35 becomes 3/7. Both forms represent the same part of a whole, just written differently. Seeing it as a percentage makes it easy to compare with other values that are already in percent form.
In everyday life, 42.86% might show up as a test score, a discount, or a portion of a budget. Knowing the percentage helps you quickly see how big or small the part is compared to the whole.
