Determine the number of months for which the total cost of the systems will be equal. Estimate your answer to the nearest whole number.

Answer:
Answer is 351/20 or 17.5
Step-by-step explanation:
Step 1: Simplify both sides of the equation.
35x+99=15x+450
Step 2: Subtract 15x from both sides.
35x+99−15x=15x+450−15x
20x+99=450
Step 3: Subtract 99 from both sides.
20x+99−99=450−99
20x=351
Step 4: Divide both sides by 20