If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( r )
r = 0
r = 0
r = 0
r in (-oo:0) U (0:+oo)
(240-60-15)/r = 50 // - 50
(240-60-15)/r-50 = 0
165*r^-1 = 50 // : 165
r^-1 = 10/33
-1 < 0
1/(r^1) = 10/33 // * r^1
1 = 10/33*r^1 // : 10/33
33/10 = r^1
r = 33/10
r = 33/10
| (t-(60+15))/r=50 | | 2x+3x+n=17 | | 4+x=36-7x | | 10(x+3)-(-9x-4)=x-2 | | 1/5+3w/15=45 | | -3x+5+7x=23+9+5 | | -9x^2+12x+3=0 | | 3t^2=48t | | (x-3)*4+1=65 | | x-3*4+1=65 | | 2tanX=-sec^2X | | 0/(-10) | | h/12-5=-17 | | A=3.14r^2+3.14(r)(s) | | -16t^2+256=0 | | a-1.5=20.5 | | 30000+250x=17615+550x | | -8=-(x+14) | | 3x/46/3 | | 49-27^3/43 | | 2a-20.8=1+1.2 | | 7x-2=343 | | M(x)=-x^2-6x-5 | | x(4-3m)+1=x(3-4m)-m^2 | | 1/x+1/2=5/6 | | 1/x+1/2 | | y=5/3x+25/3-9 | | 3/2+4 | | y+9=5/3x+25/3 | | 3/2b+4b | | P(x)=60x-x^2 | | F(x)=30+x-x^2 |