Why is the product of a rational number and an irrational number irrational

Plot a point at the y-intercept of the following function on the provided graph. 3y=-5x+7 20 points

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.

Def rotates 90 clockwise about point a to create d’ e’ f’. therefore, which equation must be true ?