Answer :
[tex]x-\ all\ questions\\\\
80\%x=24\\\\
0.8x=24\ \ \ \ | divide\ by\ 0.8\\\\
x=30
\\\\
There\ were\ 30\ qestions.[/tex]
x- all questions
x-80
x-0.8| divide by 0.8
x-30
30 questions were on the test.