John earned $36 for 8 hours of work. Earnings are directly proportional with hours worked. How much did he earn when he worked 30 hours?

What are the domain and range of the function? f(x) = -4 (sqrt)x

This is different from the first one can someone me

Janie has $3. she earns $1.20 for each chore she does and can do fractions of chores. she wants to earn enough money to buy a cd for $13.50. write an inequality to determine the number of chores, c, janie could do to have enough money to buy the cd.