If it's not what You are looking for type in the equation solver your own equation and let us solve it.
a in (-oo:+oo)
a/3 = 7 // - 7
a/3-7 = 0
1/3*a-7 = 0 // + 7
1/3*a = 7 // : 1/3
a = 7/1/3
a = 21
a = 21
| m-10=-19 | | b-3/5=-1/5 | | k/3=6 | | d-9=-97/11 | | a-8=-5 | | x-7/8=-11/40 | | a+1=7/6 | | b+7=8 | | 29/3=w+9 | | 13/8=w+5/8 | | b+1/5=51/5 | | m+2/7=9/7 | | x-1/2=13/2 | | -3/5+w=32/5 | | n+3/4=27/4 | | 59/55=d+4/5 | | a-3/4=-33/28 | | 8=d-1 | | d-8=-103/12 | | -4/7m=36/7 | | x+1/2=7/8 | | -7m=0 | | m+1=4/3 | | t-2/3=25/3 | | 4/5t=32/45 | | 1+w=11/8 | | n+1/2=7/6 | | 3x+291=13x-9 | | 7/5=n+2/5 | | 17/3=k+5 | | 16=b+6 | | 5/7d=-5/7 |