caching - Solving for hit ratio in Effective Access Time given cache access -

i given following question:

consider memory system cache access time of 10 nano sec (nsec) , memory access time of 200 nano sec (nsec). if effective access time 10% more cache access time, hit ratio?

my intuition tells me set using eat equation know: [h(memory access + tlb access) + (1-h)(2*memory access + tlb access)] , solve there.

however, solution sets 1.1*10 = 10*h + (1-h)(210) solving there ratio 189/190.

where equation use come from? have been taught 1 gave means solve problems hit ratios , access times.