Concept of Perimeter

Kayla swims at Bellefield Hall every day. Today, a section of the pool is roped off for swim team practices. Usually, Kayla travels the entire perimeter of the olympic pool, swimming 15 laps. If 4 lengthwise lanes are roped off, how many new laps must Kayla do to make sure she swims at least the same length?

Assume: $\\$ $\bullet$ An Olympic pool is 25 meters wide and 50 meters long. $\\$ $\bullet$ There are 10 length-wise lanes per olympic pool. $\\$ $\bullet$ Kayla only wants to swim complete laps.