-78.75% is the change from 240 to 51
Calculation steps:
[( 51 - 240 ) ÷ 240] x 100 = -78.75%
Formula
Percentage change = [(51 - 240) / 240] x 100
Subtract the new number by the original number
51 - 240 = -189
-189 ÷ 240 = -0.7875
-0.7875 x 100 = -78.75%