Answer: Second option, third option and fifth option.
Step-by-step explanation:
In order to solve this exercise it is important to remember the multiplication of signs:
[tex](+)(+)=+\\(-)(-)=+\\(-)(+)=-\\(+)(-)=-[/tex]
Knowing that, you can distribute the sign and add the like terms. Repeat this procedure in each expression given in the exercise.
Therefore, you get:
[tex]a.\ (3.4a - 1.7b) + (2.5a - 3.9b)=3.4a - 1.7b + 2.5a - 3.9b=5.9a-5.6b\\\\b.\ (2.5a + 1.6b) + (3.4a + 4b)=2.5a + 1.6b + 3.4a + 4b=5.9a+5.6b\\\\c.\ (-3.9b + a) + (-1.7b + 4.9a)=-3.9b + a -1.7b + 4.9a=5.9a-5.6b\\\\d.\ -0.4b +(6b - 5.9a)=-0.4b +6b - 5.9a=6b-6.3a\\\\e.\ 5.9a - 5.6b[/tex]
You can identify that the expressions [tex](2.5a + 1.6b) + (3.4a + 4b)[/tex], [tex](-3.9b + a) + (-1.7b + 4.9a)[/tex] and [tex]5.9a - 5.6b[/tex] are equivalent after simplifying.
