I believe you are expected to simplify. To do this all you do is group like terms (x, x², x³ etc.) and then simplify the coefficients.
13. 10z + 7z - 19z² - 5z² - 17z
first you can rearrange and group like terms (remember the bring the sign in front of each term with it). I would do it like this:
-19z² - 5z² +10z + 7z - 17z
Now simplify the coefficients:
-24z² + 0z
you can omit the 0z and your simplified answer is
-24z²
Main thing to remember here is that z and z² cannot be simplified together, nor can any variable that has an exponent because the exponent makes them differ.
143 cards, you can find this using the LCM or least common multiple. <span />
To get the answer of 7,280 all i can figure out is to multiply (X) 364 x 20 = 7,280 and that gives you the answer you show of 7,280.