Question

Решить (x+y):(5-z):(y+z):(9+y)=3:1:2:5

Answer 1

( Х + у ) : ( 5 - z ) = 3 : 1
X + y = 3( 5 - z )
X + y = 15 - z
••••••••••
( 5 - z ) : ( y + z ) = 1 : 2
2( 5 - z ) = y + z
10 - 2z = y + z
y = 10 - 3z
•••••••••••
( y + z ) : ( 9 + y ) = 2 : 5
5( y + z ) = 2( 9 + y )
5y + 5z = 18 + 2y
3y = 18 - 5z
•••••••••••
3( 10 - 3z ) = 18 - 5z
30 - 9z = 18 - 5z
12 = 4z
z = 3
y = 10 - 3z
y = 10 - 9 = 1
X + y = 15 - z
X + 1 = 15 - 3
X = 15 - 4
X = 11

Answer 2

Там в первом х+у=15-3z

Answer 3

Обидно ((