Consider the equation below a + 9 =23
3b + 9 =23
6c + 9 = 23

Determine whether each statement about the equations is true or false

1. False

2. True

3. True

4. False

Step-by-step explanation:

a + 9 = 23

a = 14

3b + 9 = 23

3b = 14

b = 14/3

6c + 9 = 23

6c = 14

c = 14/6 = 7/3

Statement 1: 3a = 14 x 3 = 42, which is not equal to b.

Statement 2: 7/3 is less than 14.

Statement 3: 2c = 7/3 x 2 = 14/3 = b.

Statement 4: 6c = 14 = 3b, so the value of 6c is not greater than 3b. It is just equal to.

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the   (original price) is $420.

0.7x   = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.  

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

equation image indicator

x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

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step-by-step explanation:

because i said it is