Answer:
Total cost=$73.60
Explanation:
Arithmetics To Solve Simple Problems
Sometimes the use of the most basic operations can be handy to solve problems of a variety of complexities without the use of equations or algebra. We'll approach to the solution of this question by pure logic and basic operations.
If the gift was originally meant to be paid for all 5 brothers, each one would have paid one-fifth of the cost. But since the younger brother won't be paying anything, the cost will be divided among the other four brothers, each one of which will pay now one-fourth of the cost. But this new division is $3.68 more than the previous one. If we take the difference between both fractions, we get
That fraction is the portion of the money they are paying in excess, so the total cost should be twenty times that excess, i.e.
Total cost= 20*3.68=$73.60
Let's check. Each brother should have paid $73.60/5=$14,72. But the four brothers really paid $73.6/4=$18.40. The difference is cost is $18.40-$14,72=$3.68 as required