Which represents this expression in simplest form?

15(x^2)^3

25(x^−1)^−3

From the beginning of the day the temperature rose 15 degrees so that by 4 pm it was 87 degrees. what was the temperature at the start of the day

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?