Let's interpret what's being said, and what we have to find out !
Alice has a total of 42 stamps and 5/6 of the stamps are about scenary, so we have been asked how many of the stamps are about scenary.
According to question :
[tex]\qquad \sf \dashrightarrow \: \dfrac{5}{6} \: \: of \: \: 42[/tex]
[tex]\qquad \sf \dashrightarrow \: \dfrac{5}{6} \times 42[/tex]
[tex]\qquad \sf \dashrightarrow \: 5 \times 7[/tex]
[tex]\qquad \sf \dashrightarrow \: 35[/tex]
So, Alice has 35 stamps about scenary !
