Find the value of X
X = (6/119) * (63/8) * (17/9)

Answer: Option A

Explanation:

By taking LCM we get
= $$\begin{aligned} \frac{28+14+7+4+2+1}{28} = \frac{56}{28} = 2\end{aligned}$$

Answer: Option C

Explanation:

Remember the formula, if not then cram it :)
$$\begin{aligned} 2ab = (a^2 + b^2)- (a-b)^2 \end{aligned}$$
=> 2ab = 29 - 9 = 20
=> ab = 10

Answer: Option D

Answer: Option D

Explanation:

b-[b-(a+b)-{b-(b-a+b)}+2a]
=b-[b-a-b-{b-(2b-a)}+2a]
=b-[-a-{b-2b+a}+2a]
=b-[-a-{-b+a}+2a]
=b-[-a+b-a+2a]
=b-[-2a+b+2a]
=b-b
=0

Answer: Option A

Explanation:

Tip:
As you can see, there is bar over
$$\begin{aligned} \overline{\frac{1}{4}-\frac{1}{6}} \end{aligned}$$
So their sign will be changed from - to + as
$$\begin{aligned} \frac{1}{4}+\frac{1}{6} \end{aligned}$$