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[Noman]

on a particular day, a shop sold 3 fewer laptops of brand X than two times the number of laptops of brand Y. if a customer who bought a laptop of X Brand had purchased a laptop Y brand instead of X Brand. the number of Brand X & The number of Brand Y sold would have been seen same, what is the total number of laptop sold?
A.8 B.9 C.10 D.12 E.16

[sanju09]

on a particular day, a shop sold 3 fewer laptops of brand X than two times the number of laptops of brand Y. if a customer who bought a laptop of X Brand had purchased a laptop Y brand instead of X Brand. the number of Brand X & The number of Brand Y sold would have been seen same, what is the total number of laptop sold?
A.8 B.9 C.10 D.12 E.16

Are we translating it like x = 2y - 3 and also x - 1 = y + 1?

Just solve to get x = 7 and y = 5; thus x + y = [spoiler]12 (D)[/spoiler]

[MartyMurray]

On a particular day, a shop sold 3 fewer laptops of brand X than two times the number of laptops of brand Y. If a customer who bought a laptop of X Brand had purchased a laptop Y brand instead of X Brand, the number of Brand X & The number of Brand Y sold would have been seen same. What is the total number of laptops sold?

A.8 B.9 C.10 D.12 E.16

Given the actual number sold:

X + 3 = 2Y

Given what is said about what the situation would have been were a customer to have bought a brand Y laptop instead of a brand X laptop:

X - 1 = Y + 1

X = Y + 2

Substitute Y + 2 for X in the first equation.

Y + 5 = 2Y

5 = Y

12 = Y + Y + 2

The correct answer is D.

[Matt@VeritasPrep]

This is pretty ambiguous, though: "a customer who bought a laptop of X Brand had purchased a laptop Y brand instead of X Brand ..." could mean x = y or x - 1 = y + 1, depending on the interpretation. I'd be wary of questions from this source; this phrasing is dangerously unclear.