The formula for calculating the percent of change between two values over time is:
p =(N - O)/O * 100p=N−OO⋅100
Where:
pp is the percent of change - 300%300% for this problem
NN is the New Value - what we must solve for
OO is the Old Value - $25$25 for this problem
Substituting and solving gives:
300 = (N - 25)/(25) xx 100300=N−2525×100
300 = (N - 25)/color(red)(cancel(color(black)(25))) xx color(red)(cancel(color(black)(100)))4
300 = 4(N - 25)
300/color(red)(4) = (4(N - 25))/color(red)(4)
75 = (color(red)(cancel(color(black)(4)))(N - 25))/cancel(color(red)(4))
75 = N - 25
75 + color(red)(25) = N - 25 + color(red)(25)
100 = N - 0
100 = N
N = 100
