Complex sentence: As many as 1 in 3 girls in the developing world are married before reaching the age of 18, and an estimated 1 in 9 girls in developing countries are married by age 15.
Split into simpler sentences: As many as 1 in 3 girls in the developing world are married before reaching the age of 18. An estimated 1 in 9 girls in developing countries are married by age 15.