A number equals four less than three times the number ?

2 Answers
Mar 7, 2018

See below

Explanation:

To solve this problem, you can set up the equation #x=3x-4#. Now, you must isolate the variable, or get it alone. To do this, you must add 4 to both sides.

#x+4=3x-4+4#

You are now left with #x+4=3x#. But, since we need the variable #x# by itself, you must now subtract x from both sides.

#x+4-x=3x-x#

Simplify that, and you get the equation #4=2x#. Divide both sides by #2# now, so that #x# is alone.

#4-:2=2x-:2#

Simplify, and you get your final answer of x=2.

Mar 7, 2018

The number is 2

Explanation:

This sounds rather confusing, but writing it out into an equation will help a lot in solving it.

(written:) A number equals four less than 3 times the number
(equation:) #N = 3N - 4#

Now let's isolate all parts with #N# to one side so that we can solve it. Let's subtract #3N# from both sides.
#N - 3N = cancel(3N) - cancel(3N) - 4#
#N - 3N = - 4#
#-2N = - 4#

Now let's divide by 2.
#(-2N)/2 = (- 4)/2#

#-N = - 2#

Since we have a negative sign on both sides, we can actually multiply them both by #-1# so that they will both be positive (remember that negative #xx# negative #=# positive ). This will not change their value, but it will help the answer be easier to understand.

#-N xx -1 = - 2 xx -1#

#N = 2#