\(\dfrac{(49\cdot 18)+(24\cdot 84)-(56\cdot 9)}{21} = \)

[Vincen]

\(\dfrac{(49\cdot 18)+(24\cdot 84)-(56\cdot 9)}{21} = \)

A. 1.14
B. 11.4
C. 114
D. 1,140
E. 11,400

Answer: C

Source: Princeton Review

[regor60]

Notice that the answer choices are
factors of 10 of each other, suggesting that ballpark estimates will yield a safe guess.

So, 49*18 becomes 50*20= 1000
24*84 becomes 25*100 =2500
56*9 becomes 50*10=500
21 becomes 20

Substituting:
(1000+2500-500)/20
= 3000/20 = 150

The closest answer is C,114