Ratios and Rates · Superchallenge problem

Ali and Ben walk along the same straight path. In the time Ali takes $5$ steps, Ben takes $4$ steps. But Ben's steps are longer: $2$ of Ben's steps cover the same distance as $3$ of Ali's steps. Ali starts $30$ of his own steps ahead of Ben, and they set off at the same moment in the same direction. How many steps does Ben take to catch up with Ali?