a) Ta có:
x/4 = y/3 = z/9 = x/4 = 3y/9 = 4z/36
= x+3y+4z/4+9+36
= 62/49
=> x/4 = 62/49 => x = 248/49
y/3 = 62/49 => y = 186/49
z/8 = 62/49 => z = 496/49
b) Ta có:
x/y = 9/7 => x/9 = y/7
x/9 = y/7 => x/63 = y/49
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y/z = 7/3 => y/7 = z/3
y/7 = z/3 => y/49 = z/21
x/63 = y/49 = z/21 = x-y+z / 63-49+21
= -15/35 = -3/7
=> x/63 = -3/7 => x = -27
y/49 = -3/7 => y = -21
z/21 = -3/7 => z = -9