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This problem trains for: SAT-I, AMC-8, GMAT.

Ms. Irma, the psychic, saves an amount equal to three fourths of Dr. Oobglumay expenses. Dr. Oobglumay saves only one third the amount that Ms. Irma spends. If he has an income of 1000 tollars and she has an income of 1200 tollars, what percentage of his income does he spend?

Let us make the following notation:

Dr. Oobglumay | Ms. Irma | |

Spend | x | s |

Save | y | t |

Now, let us set up some equations:

Therefore,

Adding the last two equations:

But we also know that:

Grouping favorably and substituting, we obtain:

Therefore, Dr. Oobglumay saves $800 which represents 80% of his income.