Not exactly sure which equation you meant:
3(100-b)=6b
300-3b=6b
300=9b
b= about 33
100-3b=6b
100=9b
b=about 11
First, you much find out how many houses are deliverd in 1 hour.
130/2.5=52
So 52 houses are delivered in 1 hour. Now, divide that by 312.
312/52=6
It would take 6 hours to deliver 312 houses.
Steps
find the Least Common Multiple of the denominators (which is called the Least Common Denominator).
Change each fraction (using equivalent fractions) to make their denominators the same as the least common denominator.
Then add (or subtract) the fractions, as we wish!
your denominators stay the same so its 20
3x(4x - 15) < Given
12x^2 - 45x < Distributive law of property
By the way, you are simplifying not solving. You solve equations and simplify expressions.
Given two points 
, the slope of the line passing through the two points is
So, in your case, you have
