Fred, a student at UK$,$ rents an attic apartment in an old house on Euclid Avenue. To spice up his grocery shopping experience, he frequents the Euclid Kroger store, which he finds more appealing due to the unique shoppers it attracts. Conveniently, this store is also within walking distance of his apartment. Currently equipped with $$80,$ Fred has set his sights on purchasing items from Kroger. His chosen purchases include bags of pretzels $($P$),$ priced at $$1$ each, and bottles of fruit juice $($F$),2-$liter in size, which cost $$4$ each. Fred is determined to exhaust his entire $$80$ budget.

Which of the following equation of the line that represents Fred's budget constraint?

$P=20-0\mathrm{.}25F$

$P=80+20F$

$P=20-4F$

$P=80-0\mathrm{.}25F$

$P=80+0\mathrm{.}25F$

$P=80-20F$

$P=80-4F$

$P=80+4F$