10 points for geometry please help!

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

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.

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?