с уровнением 48:(20-x)=3 и ещё одно x:(80:16)=4​

1) 48 : (20 - х) = 3

20 - х = 48 : 3

20 - х = 16

х = 20 - 16

х = 4

2) х : (80 : 16) = 4

х : 5 = 4

х = 4 ⋅ 5

х = 20

48/(20-x) = 3
48 = 3(20-x)
48 = 60 - 3x
3x = 12
x = 4

x/(80/16) = 4
x•16/80 = 4
x/5 = 4
x=20