When x=8,y=20.find y when x=42.

What? I don't understand what you mean...

X=8     y=20
x=42    y=?
⇒ 42×20÷8=105 ⇒y=105 :))

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.