4+4=free points what's answer

If (a, b) is the solution to the system of equations shown above, and a and b are integers, then what is the value of a+b?

An item not normally included in ansi recommendations, but recommended by other groups is: a) a syringe b) a blood pressure monitor c) a defibrillator d) all of the above

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.