X • 2 + 30 = 3800
1885 • 2 + 30 = 3800
3770 + 30 = 3800
3800 = 3800
Answer:
Total price = $112.70
Step-by-step explanation:
Total price of all three items without tax = 4 + 94 + 6.35
= $104.35
Total price of all three items with tax = (100% + tax) * Price
= (100% + 8%) * 104.35 = 108% * 104.35
= 1.08 * 104.35 = 112.698
≅ $112.70
(2) Explain how to use estimation to check whether your answer is reasonable:
We can use estimation to check if a result is reasonable by plugging in the answer in the original equation.
E.g. x + 4 = 10; x = 10 - 4
We get that x = 6
Plug in x = 6 in x + 4 = 10.
6 + 4 = 10. Indeed the answer was a reasonable one.
Add the last two equations to eliminate <em>x</em> :
(<em>x</em> - 2<em>y</em> - 3<em>z</em>) + (- <em>x</em> + <em>y</em> + 2<em>z</em>) = 0 + 3
- <em>y</em> - <em>z</em> = 3
<em>y</em> + <em>z</em> = -3
Subtract this from the first equation to eliminate <em>z</em>, then solve for <em>y</em> :
(2<em>y</em> + <em>z</em>) - (<em>y</em> + <em>z</em>) = -8 - (-3)
<em>y</em> = -5
Plug this into the first equation to solve for <em>z</em> :
2(-5) + <em>z</em> = -8
<em>z</em> = 2
Plug both of these into either the second or third equations to solve for <em>x</em> :
<em>x</em> - 2(-5) - 3(2) = 0
<em>x</em> = -4
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Collect like terms
Subtract sides 35
Divide sides by 25
Thus ;
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