Parts of an algebraic expression separated by plus or minus signs are

If kn = 9 cm, mn = 21 cm, rs = 42 cm, and ps = 18 cm, what is the scale factor of figure klmn to figure pqrs?

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

Una caja de galletas contiene 16 paquetes y cada una de estas tiene 12 galletas y se quieren repartir entre 6 niños ¿de cuantas galletas le toca a cada niño?