Answer:
[tex]Sum = 5a -10b+7[/tex]
Explanation:
Given
[tex]2a + 5b + 7[/tex], [tex]8a-7b+4[/tex],[tex]-5a-8b-4[/tex]
Required
Add (Missing from the question)
The summation of [tex]2a + 5b + 7[/tex], [tex]8a-7b+4[/tex],[tex]-5a-8b-4[/tex] is:
[tex]Sum = 2a + 5b + 7 + 8a-7b+4-5a-8b-4[/tex]
Collect Like Terms
[tex]Sum = 2a + 8a-5a+ 5b -7b-8b+ 7 +4-4[/tex]
[tex]Sum = 5a -10b+7[/tex]