If it's not what You are looking for type in the equation solver your own equation and let us solve it.
15=40a
We move all terms to the left:
15-(40a)=0
We move all terms containing a to the left, all other terms to the right
-40a=-15
a=-15/-40
a=3/8
| x*2+x/4=90 | | k-434=814 | | u2+97=9 | | (-8/6)/(6x)=(10/6)/(2x+6/8) | | 22-3x=2(×+6) | | 11x-1=12x+13+24 | | -2x-11=6 | | -2=x-116 | | 12x=1/16 | | 8x+4x+3+7=3x+3+8x | | 5^{2x+3}=18 | | (3x-33)=90 | | 17x+8=12x-4+42 | | 6=d+2/4 | | 7x+x^2=29 | | 4x+8/3=3/16 | | 9d/4=-9 | | x/6+2.33333-3.5*1.2=23/5 | | 9/4d=-9 | | |3.2-1.054x|=2 | | 4/x-5=7x | | 3=d=9/4 | | 4+6(x-1)=1-6(x-8) | | 3m-2=4m+4-m | | 8t^2+26t+15=0 | | (x-30)+(2x-120)+(1/2+15)=180 | | 8t^2+26t+158t=0 | | 8xx=7 | | 6/187x17/2=x | | 2y×(y×3)=2 | | -3/2+19/4+z=2 | | -7w-3/2=6/5w-6/5 |