Question 323576
Jack's stride is 64 cm long 
Jill's is 56 cm long. 
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Let them be in step after x strides
time taken by jack for x strides = x/64
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time taken by Jill for x strides = x/56
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x/56-x/64=0
64x-56x= 64*56
8x = 64*56
x= 64*56/8
x= 8*56
x=448
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It is just like taking LCM of 64 & 56