Answer:
Multiply the first equation by 4.
Step-by-step explanation:
4(x+y=3) which gives
4x+4y=12
and
4x-y=7
Then subtract the two equations and the x variable will be eliminated.
Answer:
The three unknown angles X, Y , and Z are:
X = 40, Y = 20, and Z = 120
Step-by-step explanation:
Let's name X the measure of the first angle, Y the measure of the second one, and Z that of the third one.
Then we can create the following equations:
X = 2 Y
Z = 100 + Y
and
X + Y + Z = 180
So we use the first equation and the second one to substitute for the variable X and Z in the thrid equation:
2 Y + Y + (100 + Y) = 180
4 Y + 100 = 180
4 Y = 80
Y = 80/4 = 20
Then X = 40, Y = 20, and Z = 120

where n is a whole number