[填空题]
James goes on a cross-country bike rid5vm 5/s01f-ex7fn te/s t uqw ql0leu3e which comprises of 8 k9yz td w kg),1 d0gfknu:szjp3rxic g27)1lx2m of flat terrain followed by 12 km of constant uphill sloping terrain. We know James can cycle at a speed of 24 km/hr in flat terrain, however we don't know his speed on sloping uphill terrain, and t:x 2 d7l3ugstznxzpd r ,9 k0 )gyjfcg1ki1)w2herefore denote this by x km/hr.
1.Show his average speed over the entire ride, in terms of x, can be expressed as
S(x)=$\frac{60x}{x+36}$
2.Find $S^{−1}$(x).
3.Hence find the speed he needs cycle over the sloping uphill terrain in order to obtain an average speed of 20 km/hr for the whole ride. km/h
