Question

Omae wa sinderou nani (questions in the image btw)

Answer 1

Let $a$ be the number of hours worked at Job A and $b$ the number of hours at Job B. Then

$a+b=30$

and

$7.5a+8b=234.50$

From the first equation,

$b=30-a$

and substituting this into the second gives

$7.5a+8(30-a)=234.50\implies-0.5a+240=234.50$

$\implies0.5a=5.50$

$\implies\boxed{a=11}$