Complex sentence: Elijah Yardumian, a concert pianist and a product of the Curtis Institute, served as a musical mentor to his younger brother Richard, who began composing at age 14 and began a formal study of piano, harmony, theory and counterpoint at age 21.
Split into simpler sentences: Elijah Yardumian, a concert pianist and a product of the Curtis Institute, served as a musical mentor to his younger brother Richard. Yardumian began composing at age 14 and began a formal study of piano, harmony, theory and counterpoint at age 21.