Question

2.5% of what number is 2.21

Answer 1

2.5% in decimal form is 0.025. ("What number" = n)
0.025 n = 2.21
n = 88.4

Answer 2

Y x 0.025 = 2.21

Y= 2.21 / 0.025

Y = 88.4

2.5% of 88.4 is 2.21