If it's not what You are looking for type in the equation solver your own equation and let us solve it.
m in (-oo:+oo)
(1/4)*(4-(3*m))-((4/5)*(3-m)) = 7 // - 7
(1/4)*(4-(3*m))-((4/5)*(3-m))-7 = 0
(1/4)*(4-3*m)+(-4/5)*(3-m)-7 = 0
1/4*(4-3*m)-4/5*(3-m)-7 = 0
1/4*(4-3*m)-4/5*(3-m)-7 = 0
1/20*m-7-7/5 = 0
1/20*m-42/5 = 0
1/20*m-42/5 = 0
1/20*m-42/5 = 0 // + 42/5
1/20*m = 42/5 // : 1/20
m = 42/5/1/20
m = 168
m = 168
| (3m+4)=42 | | x^2+13x+39= | | .45X+29=Y | | -2(n+3)=20 | | d/20+1=d/24+1+1/4 | | 6x^2-30x+225=0 | | -6(-4x-11)=-10(x-10) | | 6x+.12=48 | | x^2+3x-669=0 | | 6x-(-210)=84 | | X=12-2/5 | | 2/5p=2/3 | | 0.8x=x-1079 | | 82=-14-7x+23x | | 10a+10b= | | y^2+12y-36=0 | | 413.20=220+0.92x | | 22x-16-14x=4(2x-5)+4 | | 13+2x=76 | | 6-z=12 | | 2x+105=133-6+28 | | 5g+3(-7+4g)=1-g | | 17x-8x-19=53 | | x^4+2x^3-4x+2=0 | | 3r^2-22-16=0 | | 15-j=16 | | t-5/4=3/2 | | 1/4(3+x)=2 | | 6x+9+5=6x-10+6 | | 17x-8-19=53 | | 71-18=-116 | | (h/6)+(h/10)=1 |