Question 453615
Distribute sqrt(15) to both terms.
sqrt(15)(2sqrt(3) - 4sqrt(5))
= 2sqrt(15)sqrt(3) - 4sqrt(15)sqrt(5)
= 2sqrt(5)sqrt(3)sqrt(3) - 4sqrt(5)sqrt(3)sqrt(5)
= 2sqrt(5)*3 - 4sqrt(3)*5
= 6sqrt(5) - 20sqrt(3)