Since you have y alone on one side of the equation......
Use substitution and plug in 1/2x-4 for y in the other equation.
Distribute
Combine like terms
Add 8 to both sides
Divide by 4
and 
Plug this value in for x
Simplify
Multiply everything by 8 and simplify
Divide.....
Your answers are:
The inequality used to solve for x is x=750/15
I believe the answer is
26
sorry if wrong
if not an answer choice then 168.
The frictional force between the tires and the road prevent the car from skidding off the road due to centripetal force.
If the frictional force is less than the centripetal force, the car will skid when it navigates a circular path.
The diagram below shows that when the car travels at tangential velocity, v, on a circular path with radius, r, the centripetal acceleration of v²/ r acts toward the center of the circle.
The resultant centripetal force is (mv²)/r, which should be balanced by the frictional force of μmg, where μ = coefficient of kinetic friction., and mg is the normal reaction on a car with mass, m.
This principle is applied on racing tracks, where the road is inclined away from the circle to give the car an extra restoring force to overcome the centripetal force.
