2.8-(-5.1)
-(-5.1)=5.1
2.8+5.1= 7.9
Is this what you were asking?
Answer:

Step-by-step explanation:
Find the gradient of the equation

The equation will have the gradient -3x
Use the general equation of a line, and substitute the coordinates in to find the y-intercept.

(4, -6)


(0, 6)

The equation of the line is

Answer:
18. 46
19. 0.7
22. 4 3/4
23. 54.5
26. 14
27. 11.5
31. 15
etc.
Step-by-step explanation:
absolute value means that the sign in front of the # doesn't matter, you just have to look at the positive value, for example:
absolute value of 46 = 46
absolute value of - 36 = 36
(imagine the sign in front of the # isn't there)
Answer:
4
the fourth expression is a rational
Answer:
a. 
b. x = 4 (see steps below)
Step-by-step explanation:
Since the two polygons are similar, the sides are proportional to each other. Using a proportion, you can solve for 'x' using cross-multiplication and division:

Cross-multiply: 15(x + 3) = 21(x + 1)
Distribute: 15x + 45 = 21x + 21
Subtract '15x' from both sides: 15x + 45 - 15x = 21x + 21 - 15x or 45 = 6x + 21
Subtract '21' from both sides: 45 - 21 = 6x + 21 - 21 or 24 = 6x
Divide by 6 on both sides: 24/6 = 6x/6
Solve for x: x = 4