The ratio between Gloria's and Sara's present age is $4:7$ respectively. Two years ago, the ratio between their ages was $1:2$ respectively. What will be Sara's age three years hence?

If $a, b, c$ and $d$ satisfy the equations

$a+7b+3c+5d=0$

$8a+4b+6c+2d=-4$

$2a+6b+4c+8d=4$

$5a+3b+7c+d=-4$

then $\frac{\left(a+d\right)}{\left(b+c\right)}=?$

Mohan gets $3$ marks for each correct question and loses $2$ marks for each wrong question. He attempts $30$ questions and obtains $40$ marks. The number of questions solved correctly is