Let p be the prize of a pen and m the prize of a mechanical pencils. If you buy six pens and one mechanical pencil, you spend 6p+m. We know that this equals 9, because you get 1$ change from a 10$ bill.
Similarly, if you buy four pens and two mechanical pencils, you spend 4p+2m, which is 8$, because now you get a $2 change. Put these equation together in a system:

Now, if you multiply the first equation by 2, the system becomes

Subtract the second equation from the first:

Plug this value into the first equation to get

Answer:
The answer I got was 0.003
76(1.0825) is 82.27. I hope this helps have a wonderful night!
Angle SRT is undetermined by the question.
A diameter always subtends a right angle (Thales' Theorem, the first in geometry) so we can be assured SRU, STU, RUT and RST are right angles.
Don't let them fool you. This is algebra.
1
a. Replacing equals with equals
b. Adding -12 to both sides
c. Multiplying both sides by 1/9
2
a. Associativity, replacing equals
b. Adding -8 to both sides
c. Multiplying both sides by 1/9
3
a. Distributive law
b. Adding -6x to both sides
c. Multiplying both sides by -1
4.
a. Replace equals with equals
b. Add -6m to both sides
c. Add -5 to both sides
d. Multiply both sides by 1/2
5. Symmetric property
6. Distributive property
7. Reflexive property
8. Transitive property