Solve for y.
-80 + y = 80
y=0
y=-160
y = 160

y = 160

Step-by-step explanation:

The given equation is expressed as

-80 + y = 80

It is a linear equation with only one variable. The variable is y. The constants on the left hand side of the equation and the right hand side of the equation are - 80 and 80 respectively. To determine the value of the variable, y, we would eliminate the constant on the left hand side of the equation by adding 80 to the left hand side of the equation and the right hand side of the equation. It becomes

-80 + 80 + y = 80 + 80

0 + y = 160

y = 160

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."