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how do you solve 7=b-4 and a+5=-8

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mgamble83 | Student, Undergraduate | eNoter

Posted June 13, 2012 at 12:38 AM via web

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how do you solve 7=b-4

and a+5=-8

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embizze | High School Teacher | (Level 1) Educator Emeritus

Posted June 13, 2012 at 2:25 AM (Answer #1)

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Solve `7=b-4` :

We can add equal numbers to both sides of an equation (the addition property of equality): in this case add 4 to both sides to get:

`7+4=b` or `11=b` . We can then use the symmetric property of equality to rewrite as :

`b=11`

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Thus if `7=b-4` then `b=11`

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Solve `a+5=-8` :

Here we can use the addtion property of equality again; this time adding -5 to both sides to get:

`a+5-5=-8-5` or `a=-13`

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Thus if `a+5=-8` then `a=-13`

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Sources:

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atyourservice | Student, Grade 10 | Valedictorian

Posted February 23, 2014 at 8:59 PM (Answer #2)

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7=b-4   just combine like terms by adding or subtracting

7+4=b

11=b so b=11

a+5=-8

a=-8-5

a=-13

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Wiggin42 | Student, Grade 11 | Valedictorian

Posted April 25, 2014 at 11:31 PM (Answer #3)

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7 = b - 4

To get the variable b by itself, we have to negate the -4. We add 4 to both sides: 

7 + 4 = b - 4 + 4

11 = b

We do the same thing for the next one . 

a+5=-8 

To get the variable a by itself, we have to negate the +5. We subtract 5 from both sides: 

a + 5 - 5 = -8 - 5

a = -13

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jess1999 | TA , Grade 9 | Valedictorian

Posted July 19, 2014 at 1:24 PM (Answer #4)

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 7 = b - 4 and a + 5 = -8

First let's solve " b " 

 7 = b - 4 now add 4 on both sides

By adding 4 on both sides , you should get

11 = b which is your answer for " b " 

Now let's solve for " a "

a + 5 = -8 subtract 5 on both sides

By subtracting 5 on both sides , you should get

a = -13 which is yours answer for " a " 

So " a "  is -13 and " b " is 11

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