20 and five eighths TIMES 15 and three fifths??
2007-08-13 03:34:54 · 11 answers · asked by elimartinez84 1 in Science & Mathematics ➔ Mathematics
20 5/8 = 165 / 8
5 3/5 = 28 / 5
165 / 8 x 28 / 5
= 165 / 5 x 28 / 8
= 33 x 7 / 2
= 231 / 2
= 115 ½
2007-08-13 03:52:02 · answer #1 · answered by Como 7 · 1⤊ 1⤋
Well here goes ---
20 and fiveeighths will reduce to165/82574/8 and 15 and three fifths will be 78/5. So the problem is What is the value of 165/5 multiplied by 78/5.
168/5* 78/5 = 2574/8 which will be equal to 321 and sixeighths.
2007-08-13 10:49:21 · answer #2 · answered by gs7683 1 · 0⤊ 0⤋
These things are called compound fractions. They consist of a whole number and a fraction.
The trick to multiplying them is to change them to pure fractions.
20 5/8 x 15 3/5 gets rewritten as
165/8 x 78/5. You can now multiply to get 12870/40,
which can also be written as 321 3/4.
Let's just look at 15 3/5 to see how it became 78/5.
The denominator of this compound fraction is 5
(denominator is the "down" number: D=down. The top number is the numerator). So if this is to be written as a single fraction, its denominator has to be 5. Clearly, 5/5 =1, so 15 of them = 15 x 5 = 75. I now have 75/5 and 3/5. I add to get 78/5.
A note of caution here: you can NEVER NEVER add or subtract fractions unless they have the same denominator. In this case I have 75/5 and 3/5 , so I can add to get my 78/5.
For multiplication and division of fractions, the rule for identical denominators doesn't apply. Just multiply the tops, then the bottoms, and that's your answer.
I hope this helps. Good luck!
2007-08-13 10:59:50 · answer #3 · answered by Grampedo 7 · 0⤊ 1⤋
Well, to solve this problem u have two approaches, u can change both mixed numbers into improper fractions, or u can do it an easier way.
first, we need to understand (a+b)(x+y)=ax+ay+bx+by. so, in this cause a=20 b=5/8 x=15 y=3/5.
ax=20x15=300. ay=20x3/5=12 bx=5/8x15=9 3/8 by=5/8x3/5=3/8. and then, adding them alltogether, u get 321 3/4
2007-08-13 10:44:38 · answer #4 · answered by quickster94 3 · 0⤊ 0⤋
convert them first to improper fractions (multiply the whole number with the numerator)
20 5/8 = 100/8
15 3/5 = 45/5
100/8 x 45/5 = just cross multiply numerator to numerator and denominator to denominator..
4500/40 then simplify
= 112 20/40 or 112 1/2 (112 and a half)
i hope this one's correct
2007-08-13 10:47:53 · answer #5 · answered by pinemirati 2 · 0⤊ 0⤋
20 5/8 x 15 3/5
= (165/8)(78/5)
= 1287/4
= 321.75
2007-08-13 10:44:06 · answer #6 · answered by sahsjing 7 · 1⤊ 0⤋
turn it into a large fraction and cross multiply
20*8=160 so 165/8
15*5= 75 so 78/5
2007-08-13 10:44:44 · answer #7 · answered by Sarita 3 · 0⤊ 0⤋
20+(5/8)=165/8
15+(3/5)=78/5
Product is 165*78/8*5=33*39/4
=1287/4
=321+(3/4)
2007-08-13 10:46:19 · answer #8 · answered by Champoleon 5 · 0⤊ 0⤋
20 5/8 * 15 3/5
165/8 * 78/5
12,870/40
1,287/4
321 3/4
Answer: three hundred twenty-one and three fourths (321 3/4)
2007-08-17 03:21:21 · answer #9 · answered by Jun Agruda 7 · 3⤊ 0⤋
20*5/8*15*3/5
20*15*3/8
20*45/8
900/8
112.5
2007-08-13 10:41:40 · answer #10 · answered by sweety 1 · 0⤊ 0⤋