// solves an equation using earth with correct unknowns
public static Steps SolveEarth(string[] quantities)
{
ConvertUnitsInArray(quantities);
//construct an array that tells us which ones are known
if (quantities.Length != 5)
{
throw new System.ArgumentException("invalid set of quantites");
}
bool[] knowns = ConstructKnowns(quantities);
Earth solution = new Earth(knowns, quantities);
solution.DoAlgebra();
return(solution.GetWork());
}