in plain and short, we simply divide the whole by (4+1), namely 150 ÷ (4+1) and then distribute accordingly.
[tex]\bf 150\qquad 4:1\qquad \cfrac{4}{1}\qquad \qquad \cfrac{4\cdot \frac{150}{4+1}}{1\cdot \frac{150}{4+1}}\implies \cfrac{4\cdot 30}{1\cdot 30}\implies \cfrac{120}{30}\implies 120:30[/tex]
