\[c(2 + 3c)(5c - 1) =\]
\[= c\left( 10c - 2 + 15c^{2} - 3c \right) =\]
\[= c\left( 15c^{2} + 7c - 2 \right) =\]
\[= 15c^{3} + 7c^{2} - 2c\text{.\ }\]