Ineed with this. i'm struggling : /

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

Lines a and b are parallel. what is the value of x? -5 -10 -35 -55

Find the length of the normal and the angle it makes with the positive x-axis. (see pictured below)