What is the fraction to this equation 0.020

Pls help fast.

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Neveah and clint are baking muffins for the bake sale. they need to bake 30 muffins for their display case. clint has baked 4 so far, and neveah has baked 7. how many muffins (m) do they have left to bake? show your work!

Using elimination, what is -4x+2y=-12 4x+8y=-24