How does the average distance between galaxies now compare with the average distance between galaxies at the time the supernova exploded?

Stretching of the Universe results in white dwarf supernova, an observed distant had a cosmological red shift of z = 1.6, the cosmological red shift value indicates the Hubble/recession velocity or distance of the object.

The formula for these kind of problems is:

Z = ((distance now)/ (distance before)) - 1

We know, Z=1.6

So, we get:

(Distance now)/ (distance before) = 1.6 + 1 = 2.6

Explanation:

The massive cosmic explosions due to burning of stars instead of fading ends their evolution is known as supernovae. The supernovae explosion leads to dropping of matter into space at nearly nine thousand to twenty five thousand miles that is 15,000 to 40,000 km/s. These unconditional blasts produce most of the materials in the universe which includes some elements, such as iron, which helps to make up our needs and even our planets'. The Supernovae is solely responsible for produced heavy elements, so we carry the remains of these distant explosions within our own bodies.

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