Suppose it was discovered that hubble's constant, h0, was smaller than previously thought. how would this affect our estimate of the age of the universe?

The age of the universe would be larger.

Explanation:

The Hubble relation states that an astronomical object's velocity is proportional to the distance between the observer and the object.

v = dH₀

where

If the Hubble constant decreases, the velocity will decrease.

Time is determined by taking the quotient between the distance and the velocity.

T = d/v

Therefore, since the velocity decreased, the time increases. Thus, if H₀ was found to be smaller than thought, the age of the universe would be larger.