Hello, beetz!

Given: horizontal distance = 68 m

angle with respect to horizontal: 35.8°

time object spends in the air: 3.0 seconds.

Find the initial velocity.

We're expected to know this formula: .

. . where: .

We are given: .

. . Hence, we have: .

The object is on the ground when and

So we have: .

Therefore: .