Remark
This may be a little confusing, but because they are travelling in opposite directions, the distances add when you want to get how far apart they are.
d1 + d2 = 1541
Equation
Let the time this happens = t
d1 = 323*t
d2 = 347*t
323*t + 347*t = 1541 Combine like terms on the left.
670t = 1541 Divide by 670
t = 1541/670
t = 2.3 hours pass before the distance of 1541 miles are between the two planes. You might need the answer to be 2 hours 18 minutes.
Answer:
The only difference is that we line up the numbers according to the decimal point. For addition, it doesn't matter which number goes on the bottom.
First, factor out 5:
5 (x² -x -20)
We need two numbers that add to -1 and multiply to -20. -5 and 4 satisfy this.
5(x-5)(x+4)
