Answer:
21
Explanation:
42% of 42 is 84% of what number
Let the number be y
42% of 42 is 84% of y
NOTE: Of means multiplication
42/100 × 42 = 84 /100 × y
1764/100 = 84y/100
cross multiply over the equal sign
176400 = 8400y
divide by 8400
176400/8400 = 8400y/8400
y = 21
To verify
42% of 42 is 84% of a number
42% of 42 is 84% of y
42/100 × 42 = 84/100 × 21
1764/100 = 1764/100
17.64 = 17.64