Answer:
7 years
Step-by-step explanation:
Let x be number of years the populations be equal
City A's population of 1115000 is decreasing at a rate of 15000 per year.
The population is decreasing at a constant rate so we use equation
y= mx + b
where m is the slope(rate), b is the initial population
m= -15000 (decreasing) , b= 1115000
y= -15000 x + 1115000
City B's population of 698000 is increasing at a rate of 45000 per year.
m= 45000 (increasing) , b= 698000
y= 45000 x + 698000
Now we set the equations equal and solve for x
45000 x + 698000 = -15000 x + 1115000
Add 15000 on both sides
60000 x + 698000 = 1115000
Subtract 689000 on both sides
60000 x = 417000
Divide by 60000 on both sides
x= 6.95
So after 7 years the population will be equal.
