Answer:
(0,20)
Explanation:
1) we can represent the situation as coordinates
lets have # of texts be "x" variable
lets have bill be "y" as the y variable is always the dependant variable and the cost of the phone bill is dependant upon the number of texts so
y=mx+b-slope-intercept form
coordinates: (50,25) and (100,30)
slope: (30-25)/(100-50)
5/50=1/10
hence slope=1/10
y=1/10x+b
substitute in a coordinate pair into this equation
25=50*1/10+b
25=5+b
b=20
hence y intercept is (0,20)