Don't understand

b) Figure 2 shows a ride called a 'jungle swing'. Figure 2 pivot three riders strapped in a harness not to scale 4 steel cables (only 2 shown) 45 m 1 1.0m The harness in which three riders are strapped is supported by 4 steel cables. An advert for the ride states that the riders will be released from a height of 45 m above the ground and will then swing with a period of 14.0 s. It states that they will be 1.0 m above the ground at the lowest point and that they will travel at speeds of 'up to 120 km per hour'. (i) Treating the ride as a simple pendulum, show that the distance between the pivot and the centre of mass of the riders is about 49 m