Answer:
y = 72
Explanation:
Joint proportion is given by the expression;
y = kxz
Given the following values;
y = 75, x = 5 and z = 5
To find the constant, k;
75 = k*5*5
75 = 25k
k = 75/25
k = 3
Next, we find the value of y when x = 4 and z= 6
y = kxz
y = 3*4*6
y = 72