Как решить уравнения: а/48=7/12; 2/19=4/y; 12/x=2/15; 25/4=b/12

[latex] \frac{ \alpha }{48} = \frac{7}{12} \\ 12 \alpha =48*7 \\ 12 \alpha =336 \\ \alpha =336:12 \\ \alpha =28[/latex] [latex] \frac{2}{19} = \frac{4}{y} \\ 2 y=19*4 \\ 2 y=76 \\ y=38 [/latex] [latex] \frac{12}{ x} = \frac{ 2}{15} \\ 2 x=12*15 \\ 2 x=180 \\ x=90[/latex] [latex] \frac{25}{4} = \frac{b}{12} \\ 4b=25*12 \\ 4b=300 \\ b=75[/latex]