You are combining like terms, and the only like terms you can combine are 6.71c and -2.52c = 4.19c
You rearrange the variables, and enter:
-2.74c² + 4.19c + 6.13
You can have terms like:
4, 4x, 4x², 4x³ You can't combine any of these terms because they have different exponents, if they were the same variable (x + x + y = 2x + y) and have the same power/exponent (y³ and 43y³ = 44y³), you can combine them
