Answer:
-6/5
Step-by-step explanation:
3/2x - 5/4y = 15
-5/4y = -3/2x + 15
multiply each side by (-4/5)
(-4/5)(-5/4y) = (-4/5)(-3/2x + 15)
y = -6/5x - 12
rate of change: -6/5
Answer: f(x) = x - 1
He will need to mow 5 lawns.