Rene made a 90 % on her math test. If she answered 20 problems correctly , how many problems were on the test ?
1 answer:
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Answer:
In 2015 the both populations were the same and from that year the population of millennials surpassed the population of boomers
Step-by-step explanation:
x=14
Boomer: 10(14)+13y=1125
140+13y=1125
13y=1125-140
y= 985/13
y= 75.77 (75.77 millions of boomers in 2014)
Millenials: -2(14) +7y = 495
-28 +7y = 495
7y= 495+28
y= 523/7
y=74.71 (74.71 millios on millenials in 2014)
In 2014 the population of boombers were still greater than the population of millennials
The solution of the system of equations will give us the point where the populations were equalized, and from that point the population of boombers will be less than that of the millennials.
Boomers: 10x+13y = 1125
y= (-10x +1125)/13
Millenials: -2x+7y = 495
y= (2x+495)/7
We match both expressions of "y"
(-10x +1125)/13 =(2x+495)/7
cross multiply:
(-10x +1125)*7 =(2x+495)*13
-70x + 7875 = 26x + 6435
we group similar terms:
7875 -6435 = 26x+70x
1440 = 96x
x= 1440/96
x= 15
In 2015 the both populations were the same and from that year the population of millennials surpassed the population of boomers