Chapter 5 - Polynomials and Polynomial Functions - 5-7 The Binomial Theorem - Practice and Problem-Solving Exercises - Page 330: 63

$600i$

According to order of operations, we multiply from left to right. Let us multiply the first two terms first: $(-3i)(20i)(10i)=-60i^2(10i)$ With $i^2$ is $-1$, replace $i^2$ with $-1$ to simplify: $(-3i)(20i)(10i)=-60(-1)(10i)$ $(-3i)(20i)(10i)=(60)(10i)$ $(-3i)(20i)(10i)=600i$