Answer:
Let the full marks be y.
Then, the statement become : 30 marks is 40 % of y.
to solve for y;
40% of y can be written as [tex]\frac{40}{100} \times y[/tex]
Then,
from the given condition we have;
[tex]\frac{40}{100} \times y =30[/tex]
or
[tex]\frac{4}{10}y =30[/tex]
Multiply both sides by [tex]\frac{10}{4}[/tex] in above equation;
[tex]\frac{4}{10}y \times \frac{10}{4} =30 \times \frac{10}{4}[/tex]
Simplify:
[tex]y= \frac{300}{4}=75[/tex]
Then, the full marks (y) = 75.
Therefore, 30 marks is 40% of 75.
Check:
30 = [tex]\frac{40}{100} \times 75[/tex]
30 =[tex]0.4 \times 75[/tex]
30 =30 [True]