Answer:
7a + 4
Explanation:
First, let's rewrite this expression to combine like terms:
12a – 8 – 5a + 12 — I bolded the constants and underlined the expressions with variables
12a – 5a – 8 + 12 — it looks a little easier regrouped, doesn't it?
The last two terms are easy, right?
12 – 8 = 4 — simplify with subtraction
We'll focus on the first two terms now. Let's rewrite the terms with variables attached to make the subtraction easier:
a(12 – 5) = a(7) = 7a
We could also think of it this way: multiplication is just repeated addition.
12a = a + a + a + a + a + a + a + a + a + a + a + a (we just add a to itself 12 times)
5a = a + a + a + a + a (we just add a to itself 5 times)
Subtracting this expression would then look like this:
a + a + a + a + a + a + a + a + a + a + a + a – (a + a + a + a + a)
a + a + a + a + a + a + a + a + a + a + a + a – a – a – a – a – a
Five of the a values will cancel out, and to show this, we can rewrite the expression once more, like this:
a – a + a – a + a – a + a – a + a – a + a + a + a + a + a + a + a
The five a values cancel out and leave us with this:
a + a + a + a + a + a + a
How many a values are added together now? Seven of them, right? We add a to itself 7 times. We can then rewrite that expression as 7a.
Using the [12 – 8 = 4] expression from above, we add the 4 to the 7a to find our final answer: 7a + 4
I hope this helps increase your understanding of the concept! Have a great day!