Answer
See the answer below.
Work Step by Step
a) The rate equation is second order in NO $r\propto [NO]^2$ and first-order in Br2: $r\propto [Br_2]$
$r=k[NO]^2 [Br_2]$
b) Since the concentration of Br2 is tripled, so does the reaction rate by the rate equation.
c) Since the concentration of NO is halved, the reaction rate is divided by a factor of 4, by the rate equation.
