Select all the expressions that equal 6^-10

In simplified exponential notation, the expression a^2•a^-3•a 1/a 0

The highest point on earth is the peak of mount everest if you climb to the top you would be approximately 29,035 feet above sea level at remembering that amount is 5280 feet percentage of the height of the mountain would you have to climb to reach a point 2 miles above sea level

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?