Rom

$$V=\dfrac 1 3 L W H$$

Michelle's box is volume

$$V_{Michelle}\dfrac 1 3 (2.5)(1.5)(1.5)=1.875in^3$$

Cora's box is volume

$$V_{Cora}=\dfrac 1 3 (3.5)(2.5)(2.5)=7.292in^3$$

$$V_{Cora}-V_{Michelle}=7.292-1.875=5.417in^3$$

which doesn't seem to correspond with any of your choices.

The area of the whole circle is

$$A_{all}=\pi 4^2=16 \pi$$

The area of the non-shaded part is

$$A_{unshaded}=\pi 2^2 = 4 \pi$$

The area of the shaded part is the difference of these

$$A_{shaded}=A_{all}-A_{unshaded}=16\pi - 4\pi = 12 \pi$$

2(5x+3)-4x = 

10x+6-4x =

6x + 6 =

6(x+1)

$${\frac{{\mathtt{21\,730}}}{{\mathtt{44\,395}}}}{\mathtt{\,\times\,}}{\mathtt{100}} = {\mathtt{48.946\: \!953\: \!485\: \!752\: \!900\: \!1}}$$

so 48.95%

click the 2nd button then click atan

while this does have a closed form it's a nasty one involving Elliptic Integral functions.

$$\dfrac 1 4 \times \dfrac 2 7 = \dfrac{1 \times 2}{4 \times 7}=\dfrac 2 {28}=\dfrac 1 {14}$$

either hit the 2nd button first or 

click and hold any of those function buttons until it changes til the inverse function and then release

Everything CPhill says is entirely correct.  For the the real numbers.

Things are different with complex numbers and the Log function becomes rather complicated in that it becomes "multivalued" and it's domain must be restricted in order to make it a proper function.

This leads to the concepts of branch cuts and Riemann surfaces and it gets sophisticated pretty quickly.

14 = 1400%