in plain and short, we simply split the total amount by the ratios and then do the distributing, so we'll be dividing 150 by 4+1, let's do so,
[tex]\bf \cfrac{Ivan}{Tanya}\qquad 4:1\qquad \cfrac{4}{1}\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}[/tex]