Let number of driveways , she shoveled on Sunday = x
And for 4 driveways , Kendra charges = 4*11=44
Therefore,
143 = 44 + 11x
And that's the model for the given situation .
Subtracting 44 from both sides,
143-44 = 11x
99 = 11x
Dividing both sides by 11
x = 9
Therefore she shoveled 9 driveways on Sunday .