Let # be defined for all numbers a, b, c, and d by

Question

123.jpg (A) 1 (B) 2 (C) 18 (D) 38 (E) 178

Shaarang26 · Answer

x=5*2-4*1 = 6
Substituting for x:
6*2-10*1 = 2

So Answer = 2 = B

SaikatRoy · Answer

Here based on the function defined
x can be calculated as
x= (5x2)-(4x1) = 6
Now replacing x i the value needed we get
(6x2)-(10x1) = 2

Answer Is Option B

ScottTargetTestPrep · Answer

x = 5*2 - 4*1 = 10 - 4 = 6

So, the value of the second symbol is:

6*2 - 10*1 = 12 - 10 = 2

Answer: B

BrushMyQuant · Answer

Lets write the function as f(a,b,c,d) = ac - bd 
 
 x = f(5,4,2,1)

To find f(5,4,2,1) we will replace a with 5, b with 4, c with 2 and d with 1 in f(a,b,c,d) = ac - bd

=>  x = f(5,4,2,1)  = 5*2 - 4*1 = 10 - 4 = 6

Similarly, f(x,10,2,1)  = f(6,10,2,1) = 6*2 - 10*1 = 12 - 10 = 2

So,  Answer will be B 
Hope it helps!

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