Based on the graph shown to the right, whose phones cost varies directly with the amount of time spent talking? a.) mark’s only b.) nikiya’s only c.) both mark’s and nikiya’s

B. Nikiya's only

Step-by-step explanation:

Mark’s cost does not vary directly with time spent talking because the cost of 0 hours is not 0 dollars

For Nikiya’s plan, the value of the constant of variation is 15

which represents Nikiya’s cost per hour

78.59 is the mean

step-by-step explanation: