Which equation represents a line which is perpendicular to the line y=5/4x-4

The magnitude, m, of an earthquake is defined to be m=log l/s, where i is the intensity of the earthquake (measured by the amplitude of the seismograph wave) and s is the intensity of a “standard” earthquake, which is barely detectable. what is the magnitude of an earthquake that is 1,000 times more intense than a standard earthquake? use a calculator. round your answer to the nearest tenth.

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

Here is another math questions. i will keep asking different questions. 4^2x=6