Please Help me I am struggling 88 points + brainliest and rates to whoever can help me thanks

The Morris family spent 9 days at Lake Tahoe and San Francisco. They spent $350 per day at Lake Tahoe and $475 per day in San Francisco. The total cost of their trip was $3,650.

a. Write a system of equations that can be used to find how many days the Morris family spent at Lake Tahoe and in San Francisco. Be sure to define the variables you use.

b. Use the substitution method to find the number days the Morris family spent at Lake Tahoe and in San Francisco. Be sure to show (write out) your work.