Let:
* $x$ be the amount of hours weeding flower beds
* $y$ be the amount of hours mowing lawn.
So, the equation system is $$\left\\{\begin{array}08x+10y=250\\\ x+y=200\end{array}\right.$$
## Steps to solve
Multiplying the second equation by $8$ yields $$\left\\{\begin{array}08x+10y=250\\\ 8x+8y=1600\end{array}\right.$$ Subtracting the second equation from the first yields $$2y=-1350\\\ y=-675$$ Substituting that into $x+y=200$ yields $$x+(-675)=200\\\ x=200+675\\\ x=875$$ Therefore, $x=875$ and $y=-675$.