Answer
$\color{blue}{-10y^2+y}$
Work Step by Step
RECALL:
(1) $a(b+c) = ab + ac$
(2) $a^m \cdot a^n = a^{m+n}$
Use rule (1) above to obtain:
$=y^{5/8} \cdot y^{3/8} -y^{5/8} \cdot 10y^{11/8}$
Use rule (2) above to obtain:
$=y^{5/8+3/8} - 10y^{5/8+11/8}
\\=y^{8/8} - 10y^{16/8}
\\=y^1 -10y^2
\\=y-10y^2
\\=\color{blue}{-10y^2+y}$
