In order to solve the following system of equations by addition, which of the
following could you do before adding the equations so that one variable will
be eliminated when you add them?
4x – 2y = 7
3.x – 3y = 15

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

Answer soon(fast) 15 pts-brainliest? for right answer with small explination a restaurant catered a party for 40 people. a child’s dinner (c) cost $11 and an adult’s dinner (a) cost $20. the total cost of the dinner was $728. how many children and adults were at the party? use the table to guess and check.(i couldn't get the graph onto the question)                                8 children and 32 adults9 children and 31 adults10 children and 30 adults12 children and 28 adults

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?