2z - 31 = -9z + 24 can anyone tell me how to know if we must subtract or add? like we must write it as this when we solve it 2z - (- 9z) or 2z + -9z

its 4 because 2 times 2 is 4, if you double the number two you get four

0.16 or 16%

step-by-step explanation:

lets take a coin for example.

if you toss it twice, it has a 1/4 chance of landing on heads both times because 1/2 * 1/2 is 1/4.

with the cards, the chance of picking dog is 0.4. having two people pick one is like picking a card twice in a row. so 0.4 * 0.4 is 0.16, or 16%