Eva opened a bank account. she deposited $68.40 into her account every month for 20 months. she used $42.40 every month to pay for craft classes. after 20 months, she used 1 over 2 of the total money left in her account to go to a crafting summer camp. what is the total amount of money eva spent to go to the summer camp

260

Step-by-step explanation:

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%

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.