You are solving the system 10x + 15y = 20 and 5x + 6y = 8.5. After you multiply the second equation by a scalar of -2, which resulting equation is left to solve? Pls if you don't mind pls solve It my hard hurts.(it Algebra

8000 + 8800 + 8000 + 8 million + 80 trillion + another a katrillion equals

Thales was an ancient philosopher familiar with similar triangles. one story about him says that he found the height of a pyramid by measuring its shadow and his own shadow at the same time. if the person is 5-ft tall, what is the height of the pyramid in the drawing?

Abag contains 3 red marbles, 2 blue marbles, and 2 green marbles. one marble is picked, then another marble. assume that the selections are made with replacement. a) find the probability of picking two red marbles with replacement. b) find the probability of picking a red marble and a blue marble. assume the selections are made without replacement. c) find the probability of picking two red marbles without replacement. d) find the probability of picking a red marble and a blue marble without replacement.