Riddle: Out of 100 ladies attending the gala,85 had a white hand bag;75 had black shoes;60 carried an umbrella;90 wore a ring;
How many ladies must have had all four items?
Divide by 3. All the ladies had three items. The remainder shows the number of ladies who had 4.
85756090______310 / 3 = 100 + 10 remainder