Add T to both sides: $\displaystyle{K}+{T}={4}{R}\usepackage{cmbright}\Huge\$

Divide both sides by 4: $\displaystyle\frac{{{K}+{T}}}{{4}}=\frac{{{4}{R}}}{{4}}\usepackage{cmbright}\Huge\$

Simplify to: $\displaystyle\frac{{{K}+{T}}}{{4}}={R}\usepackage{cmbright}\Huge\$