7 Times a number equals 3 less than 5 times that number. What is the number?

Question

12924 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-01-11T23:23:37

The number is $-3/2$

First, let's define the number we are looking for as $n$ .

In mathematical terms "7 times as number" can be written as:

$7 xx n$ or $7 * n$ or we will use $7n$

In mathematical terms "3 less than 5 times that number" can be written as:

$5n - 3$

If these two expressions are equal we can write:

$7n = 5n - 3$

We can now solve for $n$ :

$7n - color(red)(5n) = 5n - 3 - color(red)(5n)$

$(7 - 5)n = 5n - color(red)(5n) - 3$

$2n = 0 - 3$

$2n = -3$

$(2n)/color(red)(2) = -3/color(red)(2)$

$(color(red)(cancel(color(black)(2)))n)/cancel(color(red)(2)) = -3/2$

$n = -3/2$