By what percent the number of nuclear bombs that America had was less than that of Russia after 20 years?

Direction (91-95): Study the following information and answer the questions that follow: Russia and America have some nuclear bombs initially. Everyday Russia and America buy a fixed number of nuclear bombs. The number of nuclear bombs that they buy each day is different from other’s number. After 4 years, they have equal number of nuclear bombs. After 12 years Russia has 8(16/23) % more nuclear bombs than America. After 13 years, China who has no nuclear bomb initially, took 6 nuclear bomb from Russia and 3 nuclear bombs from America, as a result now Russia has 6 nuclear bombs more than America. After 15 years, they all clubbed together their bombs and divided equally among the three. Now each of them has 142 nuclear bombs. Based on this information answer the questions that follows.