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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:

equation

equation

Therefore,

equation

equation

Adding the last two equations:

equation

equation

But we also know that:

equation

equation

Grouping favorably and substituting, we obtain:

equation

equation

equation

equation

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