8(9s+15)=6(4s-4)

8(9s+15)=6(4s-4)

 

$$\small{\text{$ \begin{array}{rcl} 8(9s+15) &=& 6(4s-4) \\ 8\cdot 9s+8\cdot 15 &=& 6\cdot 4s - 6\cdot 4 \\ 72s + 120 &=& 24s - 24 \quad | \quad - 24s\\ 72s-24s + 120 &=& -24 \\ 48s +120 &=& - 24 \\ 48s +120 &=& - 24 \quad | \quad - 120\\ 48s &=& - 24- 120\\ 48s &=& -144\\ 48s &=& -144 \quad | \quad :48\\\\ s & =& -\dfrac{144}{48} \\\\ \mathbf{s} & \mathbf{=} &\mathbf{ - 3 } \end{array} $}}\\\\\\\\ \small{\text{$\mathbf{check:} \begin{array}{rcl} 8\cdot [9(-3)+15] &=& 6\cdot [4(-3)-4]\\ 8\cdot (-27+15) &=& 6\cdot (-12-4)\\ 8\cdot (-12) &=& 6\cdot (-16) \\ -96 &=& -96 \qquad \mathrm{okay} \end{array} $}}$$