OG详解-OG2 数学1 Q27

The correct answer is  9.87. It’s given that the number a is 110% greater than the number b. It follows that a = b, or a = 2.1b. It’s also given that the number b is 90%  less than  47. It follows that b =( 1-90100​​) (47) , or b = 0.1, which yields b = 4.7. Substituting 4.7 for b in the equation a = 2.1b yields a = 2.1(4.7), which is equivalent to a = 9.87. Therefore, the value of a  is 9.87.