Question

Once a consumer reaches the point of equilibrium (which is the point of maximum satisfaction) he would not like to change his allocation of expenditure (to goods X and Y) even if price of one commodity changes. Do you agree?

Answer 1

No.
Equilibrium is struck when:
$\frac{M{U}_X}{P_X}=\frac{M{U}_Y}{P_Y}=M{U}_M$

or $\frac{M{U}_X}{M{U}_Y}=\frac{P_X}{P_Y}=M{U}_M$

Now, if $P_X$ changes, the equation of equilibrium is distributed.
In case $P_X$ increases,
$\frac{M{U}_X}{P_X}<\frac{M{U}_Y}{P_Y}$. This would prompt the consumer to buy more of Y in place of X.

In case of $P_X$ decreases,

$\frac{M{U}_X}{P_X}<\frac{M{U}_Y}{P_Y}$.

This would prompt the consumer to buy more of X in place of Y.