Four people decide to equally share the cost of starting a s

Four people decide to equally share the cost of starting a small business. If they let a fifth person join this endeavor, the cost for each one would be reduced by $20,000. What is the total cost of starting this business?

Solution

Let starting business amount =x

then cost per person = x/4

now fifth person joined so new cost per person =x/5

given that cost per person reduced by 20000

which means x/4-x/5=20000

multiply both side by 20

5x-4x=400000

x=400000

so total cost of the starting this business was $400000