Is -7+9 equal to -9+7

2x+3y=12 x-y=6 solve the following system equations

Amuffin recipe, which yields 12 muffins, calls for cup of milk for every 1 cups of flour. the same recipe calls for cup of coconut for every cup of chopped apple. to yield a batch of 30 muffins, how much flour will be needed in the mix?

Aboat costs 19200 and decreases in value by 12% per year. how much will it cost in 5 years