Problem Solving (PS) | Re: In a shipment of 120 machine parts, 5 percent were defective

Another solution:
Call x (%) is percent of the machine parts were defective for the two shipments combined.
120/80=(10-x)/(x-5)
=> 120 (x-5) = 80(10-x)
=> 20x = 140
=> x = 7 (%)

---