It took leo 3.5 hours to complete a route walking at a rate of 4.2 mph. how long would it take leo to complete the same route walking at a rate of 2.8 mph?

Pls! does anybody know a shortcut for answering these types of questions in the future?

Each month, a shopkeeper spends 5x + 14 dollars on rent and electricity. if he spends 3x−5 dollars on rent, how much does he spend on electricity? for which value(s) of x is the amount the shopkeeper spends on electricity less than $100? explain how you found the value(s).

Which of the expressions (on the photo document i inserted) together represent all solutions to the following equation? 8cos(12x)+4=-4 *the answer should be in degrees.* > i would like for someone to explain the process to find the solutions for this.