Question

the population of a certain city in 2017 was 105000 this represents a 12.5 decrease from 2010 population what was the 2010 population

Answer 1

Let's make an equation to show how to get how many people were in 105,000.
But, with a decrease, you have to decrease it from 100.
100-12.5
87.5
So it will be 87.5 of what it was previously. Now let's get to the equation.
.875x=105,000
Let's divide each side.
105,000÷.875
120,000
Let's check if this was a 12.5% decrease.
120,000×0.125
15,000
120,000-15,000
105,000
So the population of 2010 was 120,000 people.