It’s b because if Mandy goes 18 days and her friend goes 3 times the days she goes.
Given the graph, you can find information that would give you the slope intercept form of the linear model, which is:
y= mx+b
first off, you can find the y intercept, which is the number at which the line crosses the y axis. that is the b value.
the m value is the slope. slope is rise/run, which simply means the # of units it goes up/down, divided by the # of units it goes right/left.
so, after knowing your m and b values, you can plug it in the formula given above, and that's how you will end up w the equation of a line. I hope this helped!! x
C is the correct answer.<span />