i know the answer is 67/40 but i dont know how to get it please help
2007-09-16 18:44:06 · 9 answers · asked by kiana817 1 in Science & Mathematics ➔ Mathematics
= 28 / 40 + 25 / 40 + 14 / 40
= (28 + 25 + 14) / 40
= 67 / 40
2007-09-17 02:14:27 · answer #1 · answered by Como 7 · 2⤊ 0⤋
in order to add these fraction you would need a common denominator which is 40. therefore you would have to multiply 7/10 by 4, 5/8 by 5 and 7/20 by 2. in which your new equation will be 28/40+25/40+14/40 which would equal 67/40. this can also be written as 1 27/40.
2007-09-16 18:53:20 · answer #2 · answered by Draper 3 · 0⤊ 0⤋
As the lowest common multiple (LCM) of the three denominators is 40, ### put everything over 40:
7/10 = 7 x 4/(10 x 4) = 28/40; 5/8 = 5x5/(8 x 5) = 25/40; and
7/20 = 7 x 2/(20 x 2) = 14/40.
So 7/10+5/8+7/20 = 28/40 + 25/40 + 14/40
= (28 + 25 + 14)/40 = 67/40.
### One sees that the LCM is 40, because putting all the denominators into prime factor forms, one has:
10 = 2*5, 8 = 2*2*2, and 20 = 2*2*5,
so their LCM will be 2*2*2*5. (The 8 tells you that you need three 2's, and with a 5 as well, both 10 and 20 will divide into the product of them all. So the LCM = 2*2*2*5 = 8 x 5 = 40.)
Live long and prosper.
2007-09-16 18:50:47 · answer #3 · answered by Dr Spock 6 · 0⤊ 0⤋
First, you have to make the denominators all the same. They all can make 40. So: 7/10 x 4: 28/40 5/8 x 5: 25/40 7/20 x 2: 14/40 Now you can add them up. 28/40 + 25/40 + 14/40 = 67/40 Now you can turn it into a mixed fraction: 67/40 = 1 27/40 And here is your simplified version...sadly, no numbers go into 27 that go into 40 so this is your answer. Hope I helped.
2016-05-21 07:39:11 · answer #4 · answered by Anonymous · 0⤊ 0⤋
You want to find a common denominator (the number which can be divided by 10, 8 and 20)
= 40
then you multiply each fraction, numerator and denominator (top and bottom), by the number it takes to make the denominator 40
7(4)/10(4) + 5(5)/8(5) + 7(2)/20(2)
28/40 + 25/40 + 14/40
now you can add the numerators together, while the denominator stays 40
(28 + 25 + 14)/40
67/40
2007-09-16 18:54:31 · answer #5 · answered by Melissa 3 · 0⤊ 0⤋
7/10 + 7/20 =
(7/2 + 7/4) /5
7/2+7/4 =21/4
(21/4)/5 + 5/8 = {21(8/4) + 5(5)} /40 = (42+25)/40 = 67/40
2007-09-16 19:01:26 · answer #6 · answered by ss 2 · 0⤊ 0⤋
find the lowest common multiple of 10, 8 and 20 which is 40.
multiply each fraction so the denomenator is 40...
= 28/40 + 25/40 + 14/40
= (28+25+14) / 40
= 67 / 40 !!
2007-09-16 18:52:39 · answer #7 · answered by Ben B 2 · 0⤊ 0⤋
find the common denominator 40
[(7*4)+(5*5)+7*2)]/40
2007-09-16 18:51:58 · answer #8 · answered by xandyone 5 · 0⤊ 0⤋
Wouldn't answer be 1 and 27/40 ?
2007-09-16 18:53:15 · answer #9 · answered by bigchucka 4 · 0⤊ 0⤋