Question 295745
The percentage of boys in a particular class at the beginning of it is 60% . 
During the school year, 6 girls move away and are replaced by six boys making the it 75% boys.
 Find the number of boys and girls in the class at the beginning.
:
Let t = total in the class, (remains the same after 6 girls leave & 6 boys added)
:
.6t + 6 = .75t
6 = .75t - .60t
6 = .15t
t = {{{6/.15}}}
t = 40 in the class
:
:
Check by finding the no. of boys
.75(40) = 30 boys at the end of the class
.60(40) = 24 boys originally
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no. added: 6 boys