If MUx/Px > MUy/Py, then it means that satisfaction of the consumer derives from spending a rupee on Good X greater than the satisfaction derived from spending a rupee on Good Y.
The consumer will reallocate his income by substituting Good X for Good y. As the consumption of Good X increases the marginal utility derived from it goes on diminishing and reverse proposition occurs for Good y, this process will continue till MUx/Px becomes equal to MUy/Py.
