Multiply and simplify

How do i do this using elimination 2x+3y=12 x-y=6

Ricardo ran the 400 meter race 3 times his fastest time was 54.3 seconds his slowest time was 56.1 seconds if his average time was 55.0 seconds what was his time for the third race

Which graph represents the linear function below? y-3=1/2(x+2)