I dont know how to do this please help!!!​

Rai compares two cable plans from different companies. which equation gives the correct value of mm, the number of months for which plans a and b cost the same?

Answer this question only if you know the answer! 30 points and

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is