Bunuel wrote:

What is the ratio of a to b?

(1) a – b +2c = 1

(2) 3a – 8b – 2c = –1

We'll try playing around with the equations to get a ratio of a:b.

This is a Precise approach.

(1) We have no way to transform this equation into a:b.

Insufficient!

(2) Similarly to the above, we have one equation with 3 variables and no way to get to a:b.

Insufficient.

Combined:

Adding the 2 equations together causes 2c and 1 to cancel out giving 4a - 9b = 0.

Then 4a = 9b and we can solve the question! (There is no need to calculate...)

(C) is our answer

_________________

David

Senior tutor at examPAL

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