(1)
10(1+3x)=-20
Cross multiply.
10+30x=-20
Isolate x on one side. So you would subtract 10 on each side. and one side will cross each other out. leaving you with,
30x=-20-10
Subtract 10 from -20.
30x=-30
Divide each side by 30 to get x.
30x÷30=-30÷30
Therefore,
x=-1
(2)
-5x-8(1+7x)=-8
Cross multiply -8(1+7x)
-5x-8-56x=-8
Isolate all x's on one side. So you would add 8 on each side. and one side will cross each other out. leaving you with,
-5x-56x=-8+8
Add 8 to -8.
-5x-56x=0
Subtract -56x from -5x
-61x=0
Divide each side by -61
-61x÷-61=0÷-61
Therefore,
x=0
Answer:
I assume you know Arithmetic Progression .
so, we have to find the first and last 4-digit number divisible by 5
first = 1000 , last = 9990
we have a formula,
= a + (n-1)d
here,
is the last 4-digit number divisible by 5.
n is the number of 4-digit even numbers divisible by 5
d is the common difference between the numbers, which is 10 in this case
a is the first 4-digit number divisible by 5
9990 = 1000 + (n-1)*10
899 = n-1
n = 900
Hence, there are 900 4-digit even numbers divisible by 5
The answer is D, here’s why:
You know the slope-intercept form is y=mx+b
mx being the slope and b being the y-intercept.
y=-4/7x + 9 is already in that form.
A is not the answer because the y is supposed to be by itself.
B is not the answer because again, the y is not by itself.
C is not the answer because the y is also not by itself.
In the slope-intercept form, the y must be by itself and the slope (mx) and the y-intercept must be on the other side.
Hope this helps.
Answer:
Option A:
is the correct answer.
Step-by-step explanation:
Given that:
Slope of the line = 
Let,
m be the slope of the line perpendicular to the line with slope 
We know that,
The product of slopes of two perpendicular lines is equals to -1.
Therefore,

Multiplying both sides by 

m = 
is the slope of the line perpendicular to the line having slope
Hence,
Option A:
is the correct answer.
Answer
Find out the how long will it take the submarine to descend to the ocean floor
To proof
Formula

where d = distance traveled (or descended),
r = rate of travel , t = time
As given
A submarine descends at a rate of 2.6 kilometers per hour. If the ocean floor is 6.24 kilometers below sea level .
put all the values in the above formula


t = 2.4 hour
it take 2.4 hours the submarine to descend to the ocean floor .
Hence proved