Order with respect to A
For a first-order reaction:
\[t_{75\%} = 2 \times t_{50\%}.\]
This is consistent with the information given, so the reaction is first order with respect to A.
Order with respect to B The plot of [B] versus $t$ is a straight line, which indicates that the reaction is zero order with respect to B.
Overall order of the reaction:
\[\text{Order} = 1 \, (\text{w.r.t. A}) + 0 \, (\text{w.r.t. B}) = 1.\]
Final Answer:\[1.\]
The portion of the line \( 4x + 5y = 20 \) in the first quadrant is trisected by the lines \( L_1 \) and \( L_2 \) passing through the origin. The tangent of an angle between the lines \( L_1 \) and \( L_2 \) is: