The first question:
'is' in mathematics means equal
'of' in mathematics means multiplication
[tex]\frac{x}{100} \times 25 = 14\\\\\frac{x}{4} = 14\\\\\boxed{\bf{x=56}}[/tex]
56% of 25 is 14.
And the second question:
'is' in mathematics means equal
'of' in mathematics means multiplication
[tex]\frac{x}{100} \times 20 = 11\\\\\frac{x}{5} = 11\\\\\boxed{\bf{x = 55}}[/tex]
55% of 20 is 11.
And finally, the third question:
'is' in mathematics means equal
'of' in mathematics means multiplication
[tex]15 = \frac{x}{100} \times 5\\\\15 = \frac{x}{20}\\\\\boxed{\bf{x=300}}[/tex]
15 is 300% of 5.
