10. 150
11. 1250
12. 105
13. 158000
15. B
Answer:
sin(-a)= -15 /17
Step-by-step explanation:
Alright, lets remember that sin(x) is odd function, which means that
wherever you watch an expression like this: sin(-a), you can use the odd functions property, and turn it like the following
sin(-a)= - sin(a)
Now, other thing to remember: 
So, we can obtain any value for sin(x) function starting from the opposite function, cos(x), using the following:

So, if cos(a)= - 8 / 17, using the above equation we obtain the value for sin(a)

Using the odd function property, we get the following result
sin(-a)= - sin(a) = -15/17
2c + b = 37 ....multiply by -3
4c + 3b = 81
------------------
-6c - 3b = - 111 (result of multiplying by -3)
4c + 3b = 81
------------------add
-2c = - 30
c = -30/-2
c = 15 <== $ 15 for a can of paint
and it costs $ 7 for each brush
Yo I need help I’m in the 8th grade help me with this pls