## Intermediate Algebra for College Students (7th Edition)

The answer is $2280$.
For the first series ${a_n}=-5,10,-20,40,...$. Common ratio $r=-2$. This is the geometric series. Sum of the first $10$ terms. $S_{10}=\frac{-5(1-(-2)^{10})}{1-(-2)}$. Simplify. $S_{10}=1705$. And the second series is ${b_n=10,-5,-20,-35,...}$. Common difference $d=-15$. The tenth terms is. $T_{10}=10+(10-1)(-15)$ Simplify. $T_{10}=10+9(-15)$ $T_{10}=10-135$ $T_{10}=-125$ The sum of the first $10$ terms is $S_{10}=\frac{10}{2}\cdot (10-125)$ $S_{10}=5\cdot (-115)$ $S_{10}=-575$. The difference is $=1705-(-575)$ $=2280$.