Solve for x
x = \frac{21}{5} = 4\frac{1}{5} = 4.2
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105-7\left(2x+3\right)=3\times 2x
Multiply both sides of the equation by 21, the least common multiple of 3,7.
105-14x-21=3\times 2x
Use the distributive property to multiply -7 by 2x+3.
84-14x=3\times 2x
Subtract 21 from 105 to get 84.
84-14x=6x
Multiply 3 and 2 to get 6.
84-14x-6x=0
Subtract 6x from both sides.
84-20x=0
Combine -14x and -6x to get -20x.
-20x=-84
Subtract 84 from both sides. Anything subtracted from zero gives its negation.
x=\frac{-84}{-20}
Divide both sides by -20.
x=\frac{21}{5}
Reduce the fraction \frac{-84}{-20} to lowest terms by extracting and canceling out -4.
Examples
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{ 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}