4x + 3y = 65
X + y = 18
When you use elimination, multiply the second equation by -3
4x + 3y = 65
-3X -3y = -54
X = 11
X+y = 18
11 + y = 18
Y = 7
Answer:
Explanation:
opposite angles in a quadrilateral sum up to 180°
total interior angles in a quadrilateral is 360°
solve for x:
x - 2 + x + 2 = 180°
2x = 180°
x = 90°
solve for each angle:
1st
x + 2
90° + 2 = 92°
2nd
x - 2
90° - 2 = 88°
3rd
x - 10
90° - 10° = 80°
4th
360° - 80° - 88° - 92° = 100°
#1)
Answer:
x=1 and y=12
Explanation:
y=5x+7
y=2x+10
This system should use substitution because the value of y is given in terms if x.
Substitution:
5x+7=2x+10
Solve:
3x=3
x=1
Substitute x to solve for y by plugging x into one if the original equations(doesn’t matter which one is used).
y=5x+7
y=5(1)+7
y=5+7
y=12
#2)
Answer:
x=-8 and y=2
Explanation:
y=2x+18
9y=-2x+2
This system also uses substitution. The value of y us already given in terms if c in the first equations, so we will substitute in the second equation.
Substitute:
9(2x+18)=-2x+2
Solve:
18x+162=-2x+2
20x=-160
x=-8
Now that we have the value if x, plug it into one of the original equations(doesn’t matter which equation) and substitute to find y.
y=2x+18
Substitute:
y=2(-8)+18
Solve:
y=-16+18
y=2
