O 2x ++
Step by step explanation:
Cramer's rule is an explicit formula for the solution of a system of linear equations. That has many equations as unknowns and valid whenever the system has a unique solution.
We can calculate the number of hours she needs to babysit by the rule of three.
1 hour--------------------$11
x---------------------------$331
x=(1 hour x x$331) / $11=30.0909.... hours≈31 hours
She needs to work 31 hours.
