How do you solve 1/2x=40?

5 Answers

ncchemist's profile pic

ncchemist | eNotes Employee

Posted on

The solution depends on whether the x variable is in the numerator or the denominator of the fraction.  It's a little difficult to tell which one you are asking for so I will give both.

If the x is in the numerator, the equation is:


Multiply both sides by 2 to eliminate the 1/2 term on the left:



If the x is in the denominator, the equation is:


Multiply both sides by 2x:



Now divide both sides by 80:


So the answer is either x=80 or x=1/80, depending on exactly which equation you were asking about.  In the future, using parentheses in your equations can help specify exactly what you mean when typing equations.

sid-sarfraz's profile pic

sid-sarfraz | Student, Graduate | (Level 2) Salutatorian

Posted on




(1/2 )x = 40

Take 2 on both sides, as to cancel the 2 in denominator OR you can directly transpose 2 to RHS but then it will be multiplied with 40,

According to the rule, when an integer is divided (denominator) on LHS, it is when transposed then it will be multiplied to the RHS numerator and vice versa, for example;

a/b = 1 (b when transposed)

a = 1 x b

Continuing with the question,

x = 40 * 2

x = 80

Hence Solved.

Proving if the answer is right

(1/2)x = 40

Insert value of x

1/2 (80) = 40

80/160 = 40

40 = 40

Hence proved!

malkaam's profile pic

malkaam | Student, Undergraduate | (Level 1) Valedictorian

Posted on

How do you solve 1/2x=40?

In order to solve this we need to isolate the variable x, therefore

1/2x = 40

1/2x * 2 = 40 * 2              (multiply both sides by 2)

x = 80 Answer.

We can prove that the answer is correct by inserting the value of x in the equation:

1/2x = 40

1/2(80) = 40

80/2 = 40

40 = 40 

LHS = RHS proved.

atyourservice's profile pic

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on


you can do it as the 2 examples above show or you can also turn 1/2 into a decimal first:

1/2 = .5


.5x = 40

divide by .5

.5x/.5 = 40/.5

x = 80

jess1999's profile pic

jess1999 | Student, Grade 9 | (Level 1) Valedictorian

Posted on

1/2x = 40

For me , when I solve these types of equation I always remember that I should do the opposite of what the equation tells me to do . For example if it' is multiplication , I would do division . Also , always remember that you have to try to get the variable by itself . In this case , you should try to get " x " by itself . So first , you should divide by 1/2 on both sides , but since dividing fractions is basically multiplying the reciprocal you would multiply 2 on both sides . 

By dividing by 1/2 on both sides ( or multiplying by 2 ) , you should get 

x = 80 which is your answer . As you can " x " is all by itself on the left side .