Answer:
solution,
profit =Rs 1800
let the commonn multiple be 'x'
then, 4:5:9
4x:5x:9x
now,
or,4x+5x+9x = Rs 1800
or, 18x = Rs180
or, x = Rs1800÷18
or, x = Rs100
x=Rs100
again,
4x = 4 × x
= 4×100
=Rs 400
5x = 5 × x
= 5 × 100
= Rs 500
9x = 9 × x
= 9 ×100
= Rs 900
Therefore,9x= Rs900, 5x= Rs500 and 4x= Rs400.