Question

please answer this question as fast as possible with explanation. the person who will answer first will be marked as brainleist

question 7

Answer 1

Let the time taken by one man alone be xdays
And by one boy alone be ydays
So work done by each man in 1 day=1/x part
Work done by 4men in one day=4/x part
Work done by 3 men in one day=3/x part
Work done by each boy in one day=1/y part
Work done by 6 boys in one day=6/y part
Work done by 4 boys in one day=4/y part
A. To. Q
4/x+6/y=1/5
3/x+4/y=1/7
Let 1/x=a and 1/y=b
So eqns are as follows
4a+6b=1/5--------------(1)
3a+4b=1/7----------------(2)
3eq(1)-4eq(2)
12a+18b-12a-16b=3/5-4/7
2b=1/35
b=1/70
Put b in eq(1)
4a+6/70=1/5
4a=1/5-3/35
4a=4/35
a=1/35
So x =1/a=35 days
Y=1/b=70 days