SOLUTION: 3/8 - 1/9 =?

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Question 492027: 3/8 - 1/9 =?
Found 2 solutions by deborabr, ptth176:
Answer by deborabr(181) About Me  (Show Source):
You can put this solution on YOUR website!
make least common multiple of 8 and 9
just divide the numbers together by primes numbers
primes numbers are the numbers that have only two divisors: 1 and themselves
8,9|2
4,9|2
2,9|2
1,9|3
1,3|3
1,1
now multiply the divisors
2*2*2*3*3
4*2*3*3
8*3*3
24*3
72
now the fractions have equal denominators but is need divide the least common multiple that is 72 in this case by the denominator and multiply the result by the numerator
in 3/8
is like this
72/8*3 = 9*3 = 27 so 3/8 is now 27/72
and in 1/9
is
72/9*1 = 8*1 = 8 so 1/9 is now 8/72
and have
27/72 - 8/72 = (27-8)/72 = 21/72
and simplifying by 3 we have
7/24

Answer by ptth176(50) About Me  (Show Source):
You can put this solution on YOUR website!
3/8 - 1/9 =(3x9-1x8)/8x9=19/72