At a game, adult tickets were sold for $\$2.50$ each and child tickets were sold for $\$ 1.50$ each . If 400 tickets were sold and the income was $\$ 900$ each . How many adult and child tickets were sold ?

Question

$\begin{array}{1 1} a)\;Adult - 300, child - 100 \\ b)\;Adult - 200, child - 100 \\ c)\;Adult - 100, child - 300 \\ d)\;Adult - 100 , child - 200 \end{array}$