Pls help me find the operations of 3a^2+4a^2+7a^2​

Angela took a general public aptitude test and scored in the 88th percentile for aptitude in accounting. what percentage of the scores were at or below her score?

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.

Ingredient c: 1/4 cup for 2/3 serving or ingredient d: 1/3 cup for 3/4 serving which unit rate is smaller