19. use gauss-jordan elimination to solve the following system of equations. 3x + 5y = 7 6x − y = −8

the given 6 = w/p is equivalent to 6p = w, where w is the total area of the walls and p is the area covered by a single can of paint.

knowing that 6 cans of paint will be needed, 6p = w becomes 6(6) = w = 36.   this tells us that the total area to be painted is 36 square units.

1. no. 3 maps to both 3 and -2

2. yes. all x-values map to exactly 1 val.

3. no. 5 maps to both -2 and 9.

4. yes. all x-values map to exactly 1 value