I need to find the sum of 2/5 and 3/4. The LCD is 20 so I did 2x4=8 and 3x5=15. so I got 8/20 + 15/20 = 23/20, but this does not match any of the answers I have to pick from. What am I doing wrong?

Question

I need to find the sum of 2/5 and 3/4.  The LCD is 20 so I did 2x4=8 and 3x5=15. so I got 8/20 + 15/20 = 23/20, but this does not match any of the answers I have to pick from.  What am I doing wrong?

Steve · Answer

2/5 + 3/4 = 8/20 + 15/20 = 23/20 = 1.15 you are correct. answer key is bogus unless it had 1.15 as an answer

Steve · Answer

or, 1 3/20