AVakil wrote:

The weight of every type A widget is the same, the weight of every type B widget is the same, and the weight of every type C widget is the same. If the weight of 8 type A widgets is equal to the weight of 3 type B widgets, and the weight of 5 type B widgets is equal to the weight of 7 type C widgets. What is the ratio of the total weight of 1 type A widget and 1 type B widget, to the total weight of 1 type B widget and 1 type C widget?

12/23

21/40

2/3

77/96

10/7

Please explain.

[spoiler]OA is D[/spoiler]

8A=3B AND 5B=3C...let's put everything in terms of B, so ... A=3/8*B and C=5/7*B, thus (A+B)/B+C=11/8*7/12=77/96. OA must be D