Show and explain how replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions as the one shown. 8x + 7y = 39

4x – 14y = –68

Tom and maria typed in words in the ratio of 1 : 5 in 20 minutes. they typed 864 words altogether. find the number of words that each of them typed

Which expression gives the area of the triangle shown below

The sat and act tests use very different grading scales. the sat math scores follow a normal distribution with mean 518 and standard deviation of 118. the act math scores follow a normal distribution with mean 20.7 and standard deviation of 5. suppose regan scores a 754 on the math portion of the sat. how much would her sister veronica need to score on the math portion of the act to meet or beat regan's score?