If it's not what You are looking for type in the equation solver your own equation and let us solve it.
x in (-oo:+oo)
X-((1/4)*x)-((2/5)*x) = 378 // - 378
X-((1/4)*x)-((2/5)*x)-378 = 0
X+(-1/4)*x+(-2/5)*x-378 = 0
X-13/20*x-378 = 0 // - X-378
-13/20*x = -(X-378) // : -13/20
x = (-(X-378))/(-13/20)
x = -20/13*(378-X)
x = -20/13*(378-X)
| u-1/5=-5/6 | | -3(7x+9)=3x | | 4x+3x+6=9 | | 18=r-10r | | 6=n/10 | | f(x)=2/x-7 | | 21/27=a/18 | | N/3=15.5 | | 6x^3+12x^2-24x+5=0 | | 6=x+29 | | 6(c+4)-2c=-7 | | -8x-1=-9x-7 | | 49+x^2=100 | | -8x+22=-12x-14 | | 2x-13=2x-7 | | 2x-2y-4z=10 | | X^2-(12-4y)/4x | | 4x-5y+8y+x= | | A+B=300 | | 2.8=2.97 | | 5(-3x-1)+3x-1=-3 | | -13+9x=32 | | X=4e^3t | | 160-x+4x-136=180 | | -5x+15-2x=64 | | 3v^2-2v= | | 2(4x+10)=100 | | 3n=2.4 | | [3x-5]=1/2 | | b=-240+24n | | N/6=1.5 | | g(x)=x^2+3x-40 |