When dealing with exponents, you have to follow a few rules. When adding bases with exponents the base stays the same and you add the exponents. This is true for subtraction but opposite; base is same and exponents are subtracted. Multiplying through parentheses you must distribute it to all factors so for your problem (2/7) to the power of two the power goes to the 2 and the 7=2x2/7x7=4/49 so your answer should be the fraction of 4/49 4 over 49