Question

55 is $40% of what number

Answer 1

55 is 40% of what number
percent means parts out of 100
40%=40/100=4/10=2/5
'of' means multiply
55=2/5 times what number
multily both sides by 5/2 to clear fraction
275/2=what number
137.5=what number

the answer is 137.5

Answer 2

55 is 40% of 137.5

Convert the percentage (40) into a decimal by dividing it over 100:
$\frac{40}{100} = 0.4$

Divide 55 over 0.4:
$\frac{55}{0.4} = 137.5$