The total cost of a cake that serves 20 people is $35.
<u>Step-by-step explanation</u>:
- Total cost = y
- Number of additional servings = x
- The number of additional servings = 20 - 12 = 8. (x=8)
<u>The equation can be formed as</u>:
- Total cost = basic cost + (No. of additional serving
cost per additional serving)
- y = 25 + x1.25
- Substitute x=8 in the above equation
- y = 25 + 8(1.25)
- y =25+10
- y = 35
Therefore, the total cost of a cake that serves 20 people is $35.