a is given to us so just plug a into the first equation:
b-3 - 3b =9
Add 3 to both sides:
b-3b=12
Combine like terms:
-2b=12
Divide by -2 to get b by itself:
b=-6
The only answer with b as -6 is the first one, (-9,-6)
Answer:

Step-by-step explanation:
{90° = m∠1 + m∠2
{105° = 2m∠1 - m∠2
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All you have left to do is this:

So, your two angle measures are 
I am joyous to assist you anytime.
Answer:
b
Step-by-step explanation:
A proportional relationship is a straight line. Is must also go through the point (0,0)
Answer:
(1,7)
Step-by-step explanation:
SImply replace x by (1) in the expression to find the value of h:
h(1) = 4 (1) + 3 = 4 + 3 = 7
so for x = 1, h is 7 , which is written as: (1, 7)
Answer:
The total number of pants in Mary's closet = 15
Step-by-step explanation:
Here, given:
40% of slacks in her closet = 6 pairs
Let us assume the total pants in her closet = m
So, according to the given data:
40% of m = 6 pairs

⇒ m = 15
Hence the total number fo pants in her closet = 15