Need help on this one

Which matrix multiplication is possible?

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.

Solve each equation using the quadratic formula. find the exact solutions. 6n^2 + 4n - 11