Why did the cow jump over the moon?

What is the common difference in the following arithmetic sequence 7,3,-1,-5

How do i get the answer for 2/3 * 10/3

Sundar used linear combination to solve the system of equations shown. he did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. what number did sundar multiply the second equation by? 2x+9y=41 3x+5y=36