When is a protractor preferred to a ruler when finding a measurement

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

Use the distributive law to multiply. 3(4x + 5y + 6)

If x = -2, then x 2-7x+10 equals a. 0 b.20 c.28