Callie H. answered • 01/15/19
National Board Certified Teacher can help you/your child in all areas
Your goal for each equation is to get it so you have the variable (the letter) equals a number. So you need to move all the numbers with variables to one side, and all the regular numbers to the other side of the equal mark.
In order to move something from one side of the equal mark to the other, you do the opposite of however it is attached (that makes little sense -- let me show you).
7a-3=3+6a You want to move the 6a from the right to the left of the equals. Since 6a is added to the 3, you subtract 6a from both sides. That makes it go away on the right (6a-6a=0). On the left you get 1a (7a-6a=1a).
Now you have a-3=3. (1a and a are the same thing). You want to move the 3 from the left to the right. It is subtracted on the left, so you add 3 to both sides. (3+3=6 on the right side)
Now you have a=6. That is your answer.
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Let's look at the second one. 16=4x+8. Since the left side does not have a variable, let's move the 8 over there. Subtract 8 from both sides.
Now you have 8=4x. You want to get the x by itself. Since it is multiplied by the 4, you divide both sides by 4 to get the x alone. That leaves you with 2 on the left (8/4) and just x on the right. x=4.
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6r+7=13+7r
Subtract 6r from both sides. 7=13+r
Subtract 13 from both sides. -6=r
That's it.
