Which number is equivalent to 0.0000001? is it 10 to the 7 power or is it 10 to the --7 power? how do you know?

The surface area of the triangular prism is .

Three friends went on a road trip from phoenix, az, to san diego, ca. mark drove 50 percent of the distance. jason drove 1/8 of the distance. andy drove the remainder of the distance. 1. andy thinks he drove 1/4 of the distance from phoenix, az, to san diego, ca. is andy correct? 2. the distance from phoenix, az, to san diego, ca, is 360 miles. how many miles did each person drive? 3. solve the problem. what is the answer in total?

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