lab_tax.h

/**
 * Calculate the personal tax allowance of a person 
 * under the UK tax system
 * 
 * @param salary annual salary in GBP
 * @return personnal allowance amount in GBP
 */
int personal_allowance( float salary )
{
}

/**
 * Calculate the income tax of a person 
 * under the UK tax system
 * 
 * @param salary annual salary in GBP
 * @return personnal allowance amount in GBP
 */
float income_tax( float salary )
{
}