Final answer:
To solve for mass (m), rearrange the equation E = mc² to m = E / c². To solve for speed of light (c), rearrange the equation to c = √(E / m). To get the most accurate calculation, solve for the variable that you need to calculate when the mass and speed of light are given.
Step-by-step explanation:
To rearrange the equation E = mc² to solve for mass (m), we can divide both sides of the equation by the speed of light squared (c²). This gives us: m = E / c².
Similarly, to solve for the speed of light (c), we can divide both sides of the equation by mass (m) and then take the square root: c = √(E / m).
If the mass and speed of light are given, you would solve for the variable that you need to calculate. For example, if you need to find the energy, you would solve for energy (E) by using the equation E = mc².