Final answer:
To find the sum of like terms, simply add their coefficients. Adding 15x, 10x, and 2x gives 27x; adding 4z, -2z, and 5z gives 7z; adding 67v, 5v, and -78v gives -6v.
Step-by-step explanation:
When adding like terms in algebra, such as 15x, 10x, and 2x together, you simply add the coefficients (the numbers in front of the variables) because the variable part (x in this case) is the same. So, the result of adding 15x, 10x, and 2x is 27x.
The same principle applies to the like terms with the variable z. To add 4z, -2z, and 5z together, you add the coefficients 4, -2, and 5 to get 7z as the result.
Similarly, 67v, 5v, and -78v are like terms with the variable v. When you add them together, the result is -6v because 67 plus 5 minus 78 equals -6.