Jeff answered all 25 questions on his test. Every right answer he got 4 points and for each wrong answer he lost 2 points. If he got a score of 70 point how many questions did he get right.

Answer 1

R + W = 25 <--- he answered all 25 questions; so 25 = # of right +# of wrong

4R - 2W = 70 <--- score of 70

2R - W = 35 <--- divides both sides by 2

3R = 60 <-- adds the two equations in BOLD together; W cancels out

R = 20

He got 20 right and 5 wrong.

His score is 20 * 4 - 2*5 = 80 - 10 = 70