0.25(q-8) = 0.1(q+7)

bobisaka

New member
Joined
Dec 25, 2019
Messages
28
Answer: q = 18

My solution and answers are wrong.. they are as follows. I have done it in so many ways and come up with so many different answers, my head is fried. I will do it side by side with the rules in the textbook next (i'm certain i applied the PEMDAS concepts). In the mean time.. and yeah not done the efficient way, did it step by step..

0.25(q-8) = 0.1(q+7)

1/4(q-8) = 1/10(q+7)

1/4q-1/10q-2 = 0.7

10/40q-4/40q-2 =0.7

6/40q-2+2=0.7 +2

6/40q = 2.7

40(6/40q) = 40(2.7)

6q = 14.81

q = 2.45????
 

Subhotosh Khan

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20,133
Answer: q = 18

My solution and answers are wrong.. they are as follows. I have done it in so many ways and come up with so many different answers, my head is fried. I will do it side by side with the rules in the textbook next (i'm certain i applied the PEMDAS concepts). In the mean time.. and yeah not done the efficient way, did it step by step..

0.25(q-8) = 0.1(q+7)

1/4(q-8) = 1/10(q+7)

1/4q-1/10q-2 = 0.7

10/40q-4/40q-2 =0.7

6/40q-2+2=0.7 +2

6/40q = 2.7

40(6/40q) = 40(2.7)

6q = 14.81

q = 2.45????
You wrote:

40(6/40q) = 40(2.7)

6q = 14.81 108

q = 108/6 = 18
 

bobisaka

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Dec 25, 2019
Messages
28
damn, yeah i used the calculator for that bit. Must of press the wrong buttons. Nice to know i did everything else okay.. Thanks!
 

Otis

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Apr 22, 2015
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2,090
Hi bobisaka. I'm not sure why you switched back and forth between rational and decimal forms, but I will suggest picking one form or the other and using it throughout.

… 6/40q - 2 + 2 = 0.7 + 2 …
Using rational form:

6/40·q - 2 + 2 = 7/10 + 2

You seem to know fractional arithmetic, so you could have continued by reducing 6/40 to lowest terms and writing the mixed number 2+7/10 as an improper fraction.

3/20·q = 27/10

Now, we can multiply each side by 20 and then divide each side by 3, or we can combine those two steps into one: multiply each side by 20/3.

q = (27/10)(20/3)

Cancel common factors, before multiplying those fractions.

q = (9/1)(2/1)

😎
 

pka

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Jan 29, 2005
Messages
9,279
Answer: q = 18
0.25(q-8) = 0.1(q+7)
I always take the easy way out.
\(0.25(q-8)=0.1(q+7)\\25(q-8)=10(q+7)\\25q-200=10q+70\\15q=270\\q=18\)
 

Jomo

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Dec 30, 2014
Messages
5,407
40(6/40q) = 40(2.7)
Stop using your calculator blindly! In fact stop using it period as it is stopping you from thinking. 2.7 is between 2 and 3 so 40*2.7 is between 40*2 and 40*3 which is between 80 and 120. So you should have caught that 14.81 makes no sense!
 
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