Answer
$2$
Work Step by Step
RECALL:
(1) $\log_b{M}+\log_b{N}=\log_b{MN}$
(2) $\log_b{M}−\log_b{N}=\log_b{\frac{M}{N}}$
(3) $\log_b{(b^x)}=x$
Use rule (2) above to obtain:
$=\log_2{(\frac{60}{15})}
\\=\log_2{4}$
Write 4 as $2^2$ to obtain:
$=\log_2{(2^2)}$
Use rule (3) above to obtain:
$=2$