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)
(1/3)*(9*x-21)-((1/7)*(63*x-(9*y))) = 0
(1/3)*(9*x-21)+(-1/7)*(63*x-9*y) = 0
1/3*(9*x-21)-1/7*(63*x-9*y) = 0
1/3*(9*x-21)-1/7*(63*x-9*y) = 0
9/7*y-6*x-7 = 0
9/7*y-6*x-7 = 0
9/7*y-6*x-7 = 0 // - 9/7*y-7
-6*x = -(9/7*y-7) // : -6
x = (-(9/7*y-7))/(-6)
x = (7-(9/7*y))/(-6)
x = (7-(9/7*y))/(-6)
| 280+x(10)=350 | | -5(-5-5n)-3=7n-32 | | 15p+1q-5p+3q+9= | | -4b=74 | | 6x-10y=24fory | | 0.1x=0.2d(x+2) | | 47x=65x-1 | | -9x+7(-3x-6)=-64-8x | | -45-9k=9(3+7k) | | 8z+11=-5 | | 2(x)+2(3)+x=-9 | | -7-2(1+6a)=-33-6a | | x/4-8=-42 | | -12(-5+2a)=-4(1-10a) | | -10+2|6?(+7)|=x | | y^2=x+121 | | -7(2x-5)+7x=84 | | -12x+12x= | | 4x+1+3x+2+2x+3+x+4=5(x+2) | | 70/14=a | | -86-(-37)= | | 7d+12-14d-3= | | y=-0.15x^2+1.05x+4.5 | | (3x+5)/(7x-1)/4x/(7x-1) | | 22+48=a | | -360/5 | | -6+3(2n+7)=3(6n+1)-8n | | -x/9+18=40 | | 2/x+1=4/7 | | 3y+4x=26 | | 7a-5b+4= | | .7+(18-9x)= |