Eighteen subtracted from a number is 35

Question

I don't know how toi do its

Answer 1

 

Let "a number" (the number we are trying to find) be 'n'

 

n - 18  is 18 subtracted from n

n - 18 = 35   (given in problem statement)

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Here you want to get n all by itself on one side of the equation, that will tell you its value.

If I told you a = b, would you agree that a+18 = b+18?   [ Hope you said yes]  Any way, 

adding 18 to both sides changes nothing about the equality, so let's do that in our problem:

n - 18 + 18 = 35 + 18

 

Finally, carrying out the addition of 18 on each side:

  n = 53    <— that is your answer 

 

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Sometimes you will hear something like  "move the 18 from the left to the right" when you hear that, they really mean add 18 to both sides.   To start off, write out every little step, then as you have mastered it you will be doing many steps in your head very naturally.