Y=20x+5

i need to find the y-intercept

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

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.

An octagonal prism has jow many lateral faces?