Answer:
The first equation must be multiplied by -5 to eliminate x variable by addition
Step-by-step explanation:
4 x - 3 y = 1 (1)
5 x + 4 y = 9 (2)
If the second equation is multiplied by 4
5x+4y=9. ×4
We have,
20x+16y=36 (3)
The first equation should be multiplied by -5 to eliminate x variable by addition
4x-3y=1 × -5
We have
-20x+15y=-5 (4)
Add equation (3) and (4) to eliminate x variable
20x+16y=36
-20x+15y=-5
31y=31
Divide both sides by 31
y=1
Substitute y=1 into equation (1)
4 x - 3 y = 1
4x-3(1)=1
4x-3=1
4x=1+3
4x=4
Divide both sides by 4
x=1
The temperature changed a total of 14° over the course of 7 hours with an average change of 2° per hour drop.
A and T are points. On their own, they cannot define a line. So we can rule out choice A
WCR and TRA are angles. For any triple the points do not fall on the same straight line. So we cannot define any lines here. This crosses off choice B
Choice C is the answer because WC does define a line. We only need two points to form a line. Similarly CR does the same job. We draw a line marker with two arrows at each end to be placed over the letters to indicate "line".
Choice D is similar to choice D; however, it is not the answer because WT is the same line as WC. In other words, WC = WT. We haven't named a new line at all. We're simply repeating ourselves.
