How do i write, nine fewer than half a number is five more than four times a number?

What values of c and d make the equation true?

When george started his current job, his employer told him that at the end of the first year, he would receive two vacation days. after each year worked, his number of vacation days will double up to five work weeks (25days) of payed vacation. how many vacation days will he have in 4 years

Indicate the formula for the following conditions: p^c(n,r)=