A two-digit number is twice the sum of its digit. If the tens digit is 7 less than the unit digit, find the number.
Let x= the unit digit
Then y= the tens digit
<span>And 10y+x= the number
</span>x+y= the sum of the digits
<span>Now we are told that 10y+x=2(x+y) ------1st equation </span>
<span>We are also told that y=x-7 ----------- 2nd Equation </span>
<span>So our equations to solve are: </span>
(1) 10y+x=2(x+y)
<span>(2) y=x-7
</span>
Hope it helps
Answer:
80
Step-by-step explanation:
check attached picture
Answer:
By 2086
Step-by-step explanation:
The provided equation is:
, where:
A=total of population after t years
A0=initial population
k= rate of growth
t= time in years
Given information:
The final population will be 15 million, then A=15.
We start in 2000 with a 5.82 million population, then A0=5.82.
Missing information:
Although k is not given, we can calculate k by using the following statement, from 2000 to 2040 (within 40 years) population is proyected to grow to 9 million, which means a passage from 5.8 to 9 million (3.2 million increament).
Then we can use the same expression to calculate k:





Now that we have k=0.011, we can find the time (t) by which population will be 15 million:





Because the starting year is 2000, and we need 86.38 years for increasing the population from 5.8 to 15 million, then by 2086 the population will be 15 million.
Okay. To solve this problem, all we have to do is find the amount of change by subtraction. 50 - 30 = 20. You find the percent of change by writing out a proportion. Do change/original = x/100. You set it up like this to find the percentage. With the numbers plugged in, it’s 20/30 = x/100. Cross multiply in order to get 2,000 = 30x. Now, divide each side by 30 to isolate the “x”. 2,000/ 30 is 66.6666 and the 6ms repeating or 67 when rounded to the nearest whole number. The percent markup is approx. 67%.