792.02 + 101.32 - 206.76

Answer: Option A

Explanation:

$$\begin{aligned} 6.\overline{46} = 6 + 0.\overline{46} = 6 + \frac{46}{99} = 6\frac{46}{99} = \frac{640}{99} \end{aligned}$$

Answer: Option B

Explanation:

35/.07 = 3500/7 = 500

Answer: Option A

Explanation:

2.5 * 10000 / 5 = 25000/5 = 5000

Answer: Option C

Explanation:

Use following formula to solve it quickly
$$\begin{aligned} \frac{a^2-b^2}{a-b}=\frac{(a+b)(a-b)}{(a-b)} = (a+b) \end{aligned}$$
= (2.39+1.61) = 4

Answer: Option C

Explanation:

2/3 = .66, 3/4 = .75, 4/5 = .8 and 5/6 = .833

So biggest is 5/6 and smallest is 2/3

Their difference is 5/6 - 2/3 = 1/6