# Thread: Solve for X

1. ## Solve for X

Ok its probably very easy, only I cant seem to figure out the order of operations to solve for X. Heres the problem

2. Originally Posted by Dominic_089
Ok its probably very easy, only I cant seem to figure out the order of operations to solve for X. Heres the problem
$\displaystyle x - \frac{3}{2} + \frac{2}{5} = \frac{5}{7}$

Don't'cha just love fractions, though?

I'd first clear those buggers out of there by multiplying both sides of the equation by $\displaystyle 2 \cdot 5 \cdot 7 = 70$:
$\displaystyle 70 \left ( x - \frac{3}{2} + \frac{2}{5} \right ) = 70 \cdot \frac{5}{7}$

$\displaystyle 70x - 3 \cdot 35 + 2 \cdot 14 = 5 \cdot 10$

$\displaystyle 70x - 105 + 28 = 50$

Now you take it from here.

-Dan

3. You can just type that in.

x - (3/2) + (2/5) = (5/7)

...or you could learn just a hair of LaTeX

$\displaystyle x\;-\;\frac{3}{2}\;+\;\frac{2}{5}\;=\;\frac{5}{7}$

What order do you seek? Addition is commutative. Do it in any order you like.

Subtract 2/5

$\displaystyle x\;-\;\frac{3}{2}\;=\;\frac{5}{7}\;-\;\frac{2}{5}$

Add 3/2

$\displaystyle x\;=\;\frac{5}{7}\;-\;\frac{2}{5}\;+\;\frac{3}{2}$

Add up the fractions and you are done.

4. $\displaystyle \displaystyle x-\frac{3}{2}+\frac{2}{5}=\frac{5}{7}\Rightarrow x=\frac{5}{7}+\frac{3}{2}-\frac{2}{5}$

The common denominator of the fractions from the right side is 70.
$\displaystyle \displaystyle x=\frac{50}{70}+\frac{105}{70}-\frac{28}{70}\Rightarrow x=\frac{127}{70}$