$A$ student secures $90\%$,$60\%$ and $54\%$ marks in test papers with $100$,$150$ and $200$ respectively as maximum marks. The percentage of his aggregate is:

In Convent Model School,$60 \%$ of the students are boys. In an aptitude test,$80 \%$ of the girls scored more than $40$ marks (out of a maximum possible $150$ marks). If $60 \%$ of the total students scored more than $40$ marks in the same test,find the fraction of the boys who scored $40$ marks or less?

In a motor of $120$ machine parts,$5 \%$ parts were defective. In another motor of $80$ machine parts,$10 \%$ parts were defective. For the two motors considered together,the percentage of defective machine parts was (in $\%$)

$A$ man's annual income has increased by ₹ $5$ lakhs,but the tax on income that he has to pay has reduced from $12 \%$ to $10 \%$. He now pays ₹ $10,000$ more income tax. What is his initial income (in ₹ lakhs)?

$6 \frac{1}{4} \%$ of $1600 + 12 \frac{1}{2} \%$ of $800$ equals

$x$ is $30 \%$ more than $y$ and $25 \%$ less than $z$. If the value of $y$ is $₹ 300$,then what is the value (in $₹$) of $z$?