GMAT Quantitative Ability - Math Problem Solving

The following question is a sample of how a typical GMAT Quantitative Section question would look like.

Directions
Solve the problem and indicate the best of the answer choices given.

Numbers
All numbers used are real numbers.

Figures
A figure accompanying a problem solving question is intended to provide information useful in solving the problem. Figures are drawn as accurately as possible EXCEPT when it is stated in a specific problem that the figure is not drawn to scale. Straight lines may sometimes appear jagged. All figures lie in a plane unless otherwise indicated.

Question
Three friends A, B and C have lunch together. A has 8 slices of bread, B has 7 slices of bread and C has none. All three of them decide to share the bread that they have equally. C gives a sum of $3 to be split between A and B for providing him lunch. What is A's share in the $3?

(A) $1.60
(B) $1.50
(C) $2.00
(D) $1.80
(E) None of these

Answer: (D)

Explanation
Amongst the three friends, A, B and C, they have a total of 8 + 7 = 15 slices of bread.

As they shared the bread equally, each of them would have ate 5 slices of bread.

A had 8 slices with him. If he ate 5 slices, he would have given 3 slices of bread to C.

Similarly, B had 7 slices of bread with him. If he ate 5 slices, he would have given 2 slices of bread to C.

Therefore, A and B should share the $ 3 in the ratio of 3 : 2.
i.e. A should get three-fifths of $3 = (3/5)*$3 = $9/5 = $1.8