The second of two numbers is 5 more than twice the first. Their sum is 80. How do you find the numbers?

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Answer 1 · 2018-03-03T06:22:24

Write down what you know first:

We have 2 numbers, number 1 and number 2.

We also know that:

$"number 2" = "5 more than" \ 2 xx "number 1"$

$"number 1 + number 2 = 80"$

Let's name number 1 $x$ and let's name number 2 $y$ .

${(y = 5 + 2x), (x + y = 80) :}$

Now, substitute your $y$ value into your 2nd equation.

If

$y = 5 + 2x$

then

$x + (5 + 2x) = 80$

is the same as:

$1x + (5 + 2x) = 80$

Combine like terms:

$5 + 3x = 80$

Solve for $x$ :

$3x = 80 - 5$

$3x = 75$

$x = 25$

So

$y = 5 + 2(25)$

$y = 55$