Answer:
Step 1: 9(4y-1)-5y=-22
Answer:
After
months the cost will be same cost 
Step-by-step explanation:
let after
months the cost is equal.
<u>Green lawn's cost</u>
startup cost 
Per month cost 
after
month cost 
<u>yard Guard's cost</u>
Startup cost 
Per month cost 
after
month cost 
Both cost are equal

after
months the cost will be same
Cost 
X + y = 2400
y = 3x
x + 3x = 2400
4x = 2400
x = 2400/4
x = 600 <== Mrs. Storey drove 600 miles
y = 3x
y = 3(600)
y = 1800 <== Mr. Storey drove 1800 miles
Your answer would be -5/2
hope this helps :)