Four times Mark's age plus 7 is Destiny's age. Destiny is 51. What is Mark's age?

Me! 50 points! why does when we come home, our door is unlocked and there is grease on the door knob, me solve this , and i don't know what category this goes under

Atransformation t : (x,y) (x-5,y +3) the image of a(2,-1) is

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.