Math
posted by AD .
Can you please show me how choose the right answer and how to get the right answer.
Which problem situation matches the equation below?
5x+5(x+20)=500
F. five people contributed to a fundraiser each give $20 more than the basic amount requested. In all, the amount contributed by these people totaled $500. What was the basic amount requested?
G. Jamal opened two investment amounts, each with 5% simple interest per year. In one, he deposited $20 more than in the other. Together, at the end of one year, the two accounts earned $500. How much had he deposited in each account?
H. A passenger train and a freight train leave the same station at the same time and go in opposite directions, the passenger train going 20 per hour faster than the freight train. At the end of 5 hours, the trains are 500 miles apart. Find the speed of the freight train.
J. A passenger train and a freight train are 500 miles apart and travel toward each other on parallel tracks. The speed of the passenger train is 20 miles per hour faster than that of the freight train. The freight train is moving at a rate of 40 miles per hour. How long will it take the two trains to pass each other?

Try writing an equation for each problem. It's easy to make a mistake while glancing over the answer choices.

Derive an Eq for the 1st prob. If it
does not match, setup the next problem. Continue until you find the Eq
that matches.
F. Amt requested = X dollars,
Amt ea gave = (X + 20) dollars,
Eq: 5(X + 20) = 500. Not a match.
G. 1st acc. inv. X dollers.
2nd acc. inv. (X + 20) dollars.
0.05X + 0.05(X + 20) = 500.
Multiply both sides by 100 to eliminate decimals.
Eq:5X + 5(X + 20) = 50000. Not a match.
H. Freight Train speed = X mi/h.
Pass. Train speed = (X + 20)mi/h.
d1 + d2 = 500.
Eq: SX + 5(X + 20) = 500. This is it!