Answer:
If they worked together it would take 4 hours for the machines to produce 100 widgets
Explanation:
w = widgets hr = hour ph = per hour
Old machine - 50w = 5hr = 10ph
New machine - 30w = 2hr = 15ph
Old machine - 20w = 2hr
New machine - 30w = 2hr
Together - 50w = 2hr x 2
Final: 100w = 4hr
I hope this helped!