HELP I NEED HELP I WILL GIVE YOU THE CROWN pls help

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

Nicole is making carrot bread she needs 5 cups of carrots for 2 cups of sugar. what is the ratio of cups of sugar to cups of carrots that nicole will need? write the ration in three different ways

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18