Step-by-step explanation:
sadly you skipped the key word in the question.
should we check under what circumstances plan A costs more than plan B ? or costs less than plan B ?
so, I don't know which inequality to solve.
but I can tell you the facts, and you need to pick the right direction for your answer.
cost of plan A for used minutes m :
cA(m) = 1.9 + 0.06m
plan B
cB(m) = 0 + 0.07m = 0.07m
to find the intersecting point, where both plans cost the same :
1.9 + 0.06m = 0.07m
1.9 = 0.01m
m = 1.9 / 0.01 = 190 minutes
up until 190 minutes plan B is cheaper.
if there are more than 190 minutes, than plan A is cheaper.
so,
m < 190 B is cheaper
m > 190 A is cheaper
m = 190 A and B cost the same
