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What is 2 numbers you can put together to get 75,000, and multiply the smaller number by 4 and add the bigger number and get 153,000?

 Nov 10, 2015
 #1
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What is 2 numbers you can put together to get 75,000, and multiply the smaller number by 4 and add the bigger number and get 153,000?

 

Let the smaller number=x

Let the bigger number=y

 

x + y=75,000

4x* + y=153,000

 

Solve the following system:
{x+y = 75000 |     (equation 1)
4 x+y = 153000 |     (equation 2)
Swap equation 1 with equation 2:
{4 x+y = 153000 |     (equation 1)
x+y = 75000 |     (equation 2)
Subtract 1/4 × (equation 1) from equation 2:
{4 x+y = 153000 |     (equation 1)
0 x+(3 y)/4 = 36750 |     (equation 2)
Multiply equation 2 by 4/3:
{4 x+y = 153000 |     (equation 1)
0 x+y = 49000 |     (equation 2)
Subtract equation 2 from equation 1:
{4 x+0 y = 104000 |     (equation 1)
0 x+y = 49000 |     (equation 2)
Divide equation 1 by 4:
{x+0 y = 26000 |     (equation 1)
0 x+y = 49000 |     (equation 2)
Collect results:
Answer: | 
| {x = 26000
y = 49000

 Nov 10, 2015
 #2
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If i were you i would try using simeltaneous equations;

lets designate the smaller number as X

and the larger number as Y

using this all the equations you can get are;

 

X + Y = 75000 (lets call this equation A)

4X + Y = 153000 (lets call this equation B

 

cool? - anyway now we have to get rid of one of the unknowns

 

Equation A - Equation B should do it (notice the presence of a singe Y in each one)

 

(X - 4X) + (Y - Y) = (153000 - 75000)

 

the Ys cancel so we get

 

3X = 78000

X = 26000

 

now we have X, Y is easy - you just put the value of X into any of the equations

 

soooo;

26000 + Y = 75000

Y = 75000 - 26000

Y = 49000

 

i didn't use a calculator, so the actual values may be off

nonetheless the meathod is solid

ta!

 Nov 10, 2015

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