Short Answer 
The function c(n) = 50 + 4n calculates the monthly cost based on the number of visits, n. By substituting n with 7, the calculation shows that c(7) equals 78 dollars.
Step 1: Understand the Function
The function is defined as c(n) = 50 + 4n, where n represents the number of visits. The function calculates the monthly cost in dollars based on the number of visits. To find a specific cost, you will substitute the value of n into this equation.
Step 2: Substitute the Value
To find c(7), replace n in the equation with 7. Follow these calculations:
- Start with: c(7) = 50 + 4n
- Now substitute n with 7: c(7) = 50 + 4(7)
- Calculate the multiplication: c(7) = 50 + 28
Step 3: Calculate and Conclude
Now, complete the final arithmetic to find c(7). Simply add 50 and 28 to get the result:
- c(7) = 50 + 28 = 78
Therefore, the value of c(7) is 78 dollars.