Question

a) x supra 5 =y supra 6= z supra 7 x+y+z=900

Answer 1

x + y + z = 900
---------------------/--------------
x / 5 = y / 6 = z / 7 = K
x / 5 = K => x = 5 K
y / 6 = K => y = 6 K
z /  7 = K => z = 7 K

5 K + 6 K + 7 K = 900
11 K + 7 K = 900
18 K = 900
K = 900 : 18
K = 50

x = 50 x 5 = 250
y = 50 x 6 = 300
z = 50 x 7 = 350