If it's not what You are looking for type in the equation solver your own equation and let us solve it.
w in (-oo:+oo)
(2/3)*w+(5/7)*w-3 = 8/7 // - 8/7
(2/3)*w+(5/7)*w-(8/7)-3 = 0
(2/3)*w+(5/7)*w-8/7-3 = 0
29/21*w-29/7 = 0 // + 29/7
29/21*w = 29/7 // : 29/21
w = 29/7/29/21
w = 3
w = 3
| -3+2/3w+3/7w=-155/21 | | -3+2/3m=5m-22/3 | | -3+2/3m=1/2m-28/9 | | -3+2/3m=-25/9 | | -3+2/3k=1/3k-53/18 | | -3+1/5w-7w=-389/5 | | -3+1/3t=-98/33 | | -3+1/2x-2/3x=-37/12 | | 5x-8/y^2 | | -3+1/2w=-13/2 | | -3+1/2n=4n-3 | | -3+1/2k=4/7k-421/140 | | -3+1/2b-2/3b=-1 | | -2x=-3/4 | | -2x=-12/7 | | -2x-8=x+19 | | -2x-8=-14/3+2x | | -2x-8+1/6x=-91/10 | | -2x-7/9=-3/5x-119/72 | | -2x-7/10+3/5x=-77/40 | | -2x-6=-13/2 | | -2x-5/9-3/7x=-5/9 | | -2x-5=-6x+31 | | -2x-4/9=14/9 | | (2)5x=(2)3x+10 | | -2x-4/7=4/7x-5/2 | | -2x-4=-49+7x | | -2x-3/4=47/44 | | -2x-3-3x=-28 | | -2x-2/3+1/7x=298/21 | | -2x-10=2x-30 | | -2x-1/9=-109/9 |