Suppose that Jim uses his budget to purchase100 units of Good X and 100 units of Good Y. When the price of Good X rises, he purchases50 units of Good X and 95 units of Good Y. An economist calculates his compensated budget and finds that in that scenario, Jim would buy80 units of Good X and 105 units of Good Y.

Calculate the income effect.

(Remember to include a negative sign (-) if the effect reduces the quantity.)