If it's not what You are looking for type in the equation solver your own equation and let us solve it.
D( x )
x/40 = 0
x/40 = 0
x/40 = 0
1/40*x = 0 // : 1/40
x = 0
x in (-oo:0) U (0:+oo)
7 = 900/(x/40) // - 900/(x/40)
7-(900/(x/40)) = 0
7-36000*x^-1 = 0
-36000*x^-1 = -7 // : -36000
x^-1 = 7/36000
-1 < 0
1/(x^1) = 7/36000 // * x^1
1 = 7/36000*x^1 // : 7/36000
36000/7 = x^1
x = 36000/7
x = 36000/7
| 0=7x-12 | | 10(6p+5)=-5(3p+91) | | -7x+3=2x-6 | | 4t^2-15t+12=0 | | 16=1/9x^2 | | 10m-2.5=9.35 | | 2x+9-6x=14 | | 3u+2u=1 | | y=4x+2-3 | | -5x+5(-4x-12)=190 | | 8/3c-2=2/3c-2 | | 2j-8=2 | | 2x+6=3x+10 | | 50+h=310 | | 2[c+4]+8=10 | | 1x-5x=17 | | 31.4=2(3.14) | | 6x-6(2x+11)=-30 | | y=-4x+2-6 | | x=x^2-7x-8 | | 2/3x10/6 | | 18x-5-16x=16x+3-16x | | 2x+1b=2b | | 201-y=242 | | 216x+2=6 | | 138=-7(5a+2)-3a | | -3r+2=-6-6r-6r | | 12w=34 | | 7(4n+9-3p+8n)= | | 18-2/4 | | 4+x-2[x-6]=8 | | 7r+8(r+2)=121 |