Usually when you do expressions involving subtraction you can do Keep, Change ,Change
That means you keep the sign of the first number and change the other two signs.
It is best you rewrite the expression to addition because a lot of people don't do well with subtracting .
If you make a proportion,
12 18
--- = ---
10 x
when you cross multiply
12x=180
x=15
EF= 15
Answer:
I can't see ;-; show close up
The solution (x,y) needs to work in both equations. With multiple choice you can do guess and test method. Otherwise you need to combine the two equations into one by substitution or elimination methods.
21. substitution works well here since one equation is y= x+3. you can easily substitute the (x+3) for y in the other equation.
2x + (x+3) = -6
3x + 3 = -6
3x = -9
x = -3
use this in either equation to find y.
y = (-3)+3
solution: (-3,0)
22. these both equal y so they equal each other.
4x - 1 = 3x +6
4x - 3x = 6 + 1
x = 7
use this in either equation to find y
y = 4(7) - 1
y = 28 - 1
y = 27
solution: (7,27)
23. one equation is y = 2x - 3. So substitute (2x -3) for y in the other equation.
4x = 2(2x - 3) + 6
4x = 4x - 6 + 6
4x = 4x
x = x
any solution will work, infinitely many.
24. infinitely many solutions means the two equations are the same equation. Like the previous one they didn't look the same but if you put them both in terms of y...
y= 2x-3
4x = 2y + 6
4x - 6 = 2y
(4x - 6)/2 = y
2x - 3 = y
same equation.
from the image, I can't see all options but A & C do not look like the same equations. It's got to be either B or D.
Answer:
3/20
Step-by-step explanation:
The total number of marbles is
3 red marbles+ 2 blue marbles+ 5 green marbles = 10 marbles
P(1st marble is red) = red marbles/total
=3/10
We replace the marble so there are still 10 marbles in the bag
P(2nd marble is green) = green marbles/total
=5/10 = 1/2
P(1st red, 2nd green) = P(1st marble is red) * P(2nd marble is green)
=3/10 *1/2
=3/20
