Let $\mathcal{r}$ be the circle centered at $(0,0)$ with radius $10. $ the lines $x = 6$ and $y = 5$ divide $\mathcal{r}$ into four regions $\mathcal{r}_1$, $\mathcal{r}_2$, $\mathcal{r}_3$, and $\mathcal{r}_4$. Let $[\mathcal{r}_i]$ denote the area of region $\mathcal{r}_i$. If \[[\mathcal{r}_1] > [\mathcal{r}_2] > [\mathcal{r}_3] > [\mathcal{r}_4],\]then find $[\mathcal{r}_1] - [\mathcal{r}_2] - [\mathcal{r}_3] + [\mathcal{r}_4]$.

An ecosystem is shown in the illustration. assume that human activities have led to a decrease in the number of eagles. a virus attack on rabbits has led to a decrease in their population in the ecosystem. which two sentences describe likely effects on the ecosystem? 1. there’s an increase in the number of snakes and insects and a decrease in the number of frogs. 2. there’s an increase in the number of snakes and insects, and the storks face increased competition for food. 3. there’s an increase in the number of storks and a decrease in the number of snakes and insects. 4. there’s an increase in the number of frogs and a decrease in the number of storks and insects. 5. there’s a decrease in the number of snakes, insects, and frogs.