Does anybody understand the 3rd problem?

Step-by-step explanation:

if you add all the angles in a triangle together, its 180 degrees.

so, (3x+2)+(4x+1)+(2x+1) = 180

we can combine like terms so 9x+4=180

                                                    9x=176

                                                       x=19.6 degrees

now plug the x into each angle and that's them

687.09 dollars       happy now

step-by-step explanation: 6870

1857 times .63 equals 1169.91 subtract that from 1857 you get 687.09

345

step-by-step explanation: