Lets consider
Total number of tenants = T
number of tenants who support proposition X = X
number of tenants who support proposition Y = Y
number of tenants who support proposition X nor proposition Y = B
number of tenants who support neither proposition = N
number of tenants who support only X = Ox ( X not Y)
number of tenants who support only Y = Oy ( Y not X)
we need to find ration of Ox / Oy = ?
From question we can observe that
X = Ox + B ------> equation 1
Y = Oy + B ------> equation 2
Now, lets try to understand the 3 ratios given in question
1) Ratio of X and B = 3:2
X/B = 3/2 -------> first ratio
X = 3*B/2
lets substitute X value in equation 1 , such that 3B/2 = Ox + B => 3B/2 - B = Ox
B/2 = Ox -------> equation 3
Therefor we can observe that, number of tenants who support only proposition X are half the number of tenants who support both proposition X and proposition Y
2) Ratio of Y and B = twice the first ratio
Y/B = 2*(3/2)
Y/B = 3
Y = 3*B
let substitute Y value in equation2 , such that 3B = Oy + B => 3B -B = Oy
2B = Oy-------> equation 4
Therefor we can observe that, number of tenants who support only proposition Y are twice the number of tenants who support both proposition X and proposition Y
3) Ratio of N(neither) to B [Note : no need to find this, above equation 3 and equation 4 are enough to answer]
N/B = half the first ratio
N/B = 1/2 * (3/2) = 3/4
N = (3/4)*B
Therefor we can observe that, number of tenants who support neither proposition X nor proposition Y is (3/4) of number of tenants who support both proposition X and proposition Y
Now, lets divide equation 3 / equation 4, i.e.,
Ox = B/2
Oy = 2B
Ox/Oy = 1/4 [Note : cancel B]
Therefor, Ox:Oy = 1:4