What is the simplified from of the expression? r^-7 + s^-12

Askyscraper is 396 meters tall. at a certain time of day, it casts a shadow that is 332 meters long.at what angle is the sun above the horizon at that time?

Lola says these two expressions have the same value. expression a expression b which explains whether lola is correct?

Sara has 2 2/3 cup taco meat. she needs 1/6 cup to make one taco. how many tacos can sara make with the taco meat she has?