We know that z varies directly as √√x and inversely as y, which can be written as:
z = k(√√x)/y
where k is the constant of proportionality.
To find the value of k, we can use the values given when x = 25 and y = 7:
179 = k(√√25)/7
179 = k(5/7)
k = (179*7)/5
k = 250.6
Now we can use this value of k to find z when x = 64 and y = 4:
z = 250.6(√√64)/4
z = 250.6(2)/4
z = 125.3
Therefore, z ≈ 125.3 when x = 64 and y = 4.