Solve for r
r=9
Share
Copied to clipboard
r+4r-20=2r+7
Use the distributive property to multiply 4 by r-5.
5r-20=2r+7
Combine r and 4r to get 5r.
5r-20-2r=7
Subtract 2r from both sides.
3r-20=7
Combine 5r and -2r to get 3r.
3r=7+20
Add 20 to both sides.
3r=27
Add 7 and 20 to get 27.
r=\frac{27}{3}
Divide both sides by 3.
r=9
Divide 27 by 3 to get 9.
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}