Solve for x
x=3.9
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\frac{8.4}{4}=6-x
Divide both sides by 4.
\frac{84}{40}=6-x
Expand \frac{8.4}{4} by multiplying both numerator and the denominator by 10.
\frac{21}{10}=6-x
Reduce the fraction \frac{84}{40} to lowest terms by extracting and canceling out 4.
6-x=\frac{21}{10}
Swap sides so that all variable terms are on the left hand side.
-x=\frac{21}{10}-6
Subtract 6 from both sides.
-x=\frac{21}{10}-\frac{60}{10}
Convert 6 to fraction \frac{60}{10}.
-x=\frac{21-60}{10}
Since \frac{21}{10} and \frac{60}{10} have the same denominator, subtract them by subtracting their numerators.
-x=-\frac{39}{10}
Subtract 60 from 21 to get -39.
x=\frac{39}{10}
Multiply both sides by -1.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}