x / y = 1/2 => x = 0,5y
y / z = 3/5
x + y + z = 38
1.5y + z = 38
5y = 3z
z = 5/3y
3/2y + 5/3y = 38
умножим обе части на 6
9y + 10y = 228
19y = 228
y = 12
z = 5/3 * y = 5/3 * 12 = 20
ответ: z = 20
x / y = 1/2 => x = 0,5y
y / z = 3/5
x + y + z = 38
1.5y + z = 38
5y = 3z
z = 5/3y
3/2y + 5/3y = 38
умножим обе части на 6
9y + 10y = 228
19y = 228
y = 12
z = 5/3 * y = 5/3 * 12 = 20
ответ: z = 20