Answer:
Ernest's calculation was correct
Explanation:
we know that
The formula to calculate the slope between two points is equal to
we have the points
A(60,900),B(15,450)
Remember that
![m_A_B=m_B_A](https://img.qammunity.org/2020/formulas/mathematics/middle-school/79eowqrlgg69t9403mdvwup4mqq2xe3rjd.png)
step 1
Find
![m_A_B](https://img.qammunity.org/2020/formulas/mathematics/middle-school/rtjwzjzk0ufctqknwjabyj3e90frwiry5m.png)
substitute in the formula
step 2
Find
![m_B_A](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1al256006au24rw287dkrvzznrs8bt1nrp.png)
substitute in the formula
therefore
Ernest's calculation was correct, because
![m_A_B=m_B_A](https://img.qammunity.org/2020/formulas/mathematics/middle-school/79eowqrlgg69t9403mdvwup4mqq2xe3rjd.png)