This question is based on load factors and speed with the question asking you to determine the change in speed.

 

Note: The aircraft is in steady level flight so the original load factor will be 1g

 

Furthermore Lift is proportional V^2 and lift is also proportional to load factor

It follows that Load factor is proportional to V^2

New LF / Original Load Factor = (new speed / original speed)^2

New speed = 300 x SQRT (1.2 / 1) = 329 kt

The speed therefore increases by 30 kt