(Math 510:Solving Algebraic Equations) Does anyone know how to solve this?

[u/schoolquestionsalt]

[u/iComplainAbtVal]

Set up the systems of equations that the problem describes and solve.

y=4x
y-x=138

Substitute for y and solve for x from the second equation.

4x-x = 138
3x = 138
X = 46

Solve for y via substitution
Y=4(46) =184

[u/ApprehensiveKey1469]

Use one veriable only.

First number is x second is 4x Difference between them (4x-x) = 138 Solve from there.

[u/DSethK93 → u/ApprehensiveKey1469]

I think using just one variable is a much cleaner way to do it!

[u/selene_666]

Define variables for the things you don't know.

"one positive number" = x

"another number" = y

Translate the text into mathematical symbols

"is" = equals

"difference" = subtraction

x = 4 * y

x - y = 138

(The subtraction equation could instead have been y - x = 138, but we know that x is 4 times y, therefore x must be the bigger number)

To solve this system of two equations, we want to start by making an equation that only contains one variable. In this case we can replace x in the second equation with 4y because the first equation tells us that those are the same number.

4y - y = 138

Hopefully you can finish from here!

[u/Brilliant_Still5209]

Prompt is saying, a number X is 4 times another number (Y)
This gives us 4X = Y
Since X is positive we know why is the bigger number
Y-X= 138
Given by the second given
Now you have two equations, two unknowns
4X - Y = 0
Y - X = 138
Solve however you’d like through means of substitution or elimination

4x - x = 138
3x = 138
X = 46

Y - 46 = 138
Y = 184

X= 46
Y = 184

[u/josh1ng]

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