I need help understanding a math question I am taking college Math

Question

 

1. Simplify the algebraic expression

5xy - 3yz - 5xz + yz - 4xz + 7xy

and evaluate it for x = 10, y = -4, z = -6. 

Identify the variables, constants, and coefficients in the simplified expression.

Answer 1

1. Simplify the algebraic expression

5xy - 3yz - 5xz + yz - 4xz + 7xy

you find the like terms:

5xy and +7xy     - 3yz and +yz        -5xz and - 4xz

there like terms if they have the same variables/exponents

 

THen you rewrite the problem with like terms next to eachother:

5xy  + 7xy  -3yz  +yz  -5xz  - 4xz

Then you solve the like terms by themselfs:

5xy + 7 xy= 12 xy

-3yz +yz= -2yz

-5xz -4xz= -9xz

so the answer is 12xy -2yz-9xz and you can't simplify it any more because none of them are like terms