Answer: 25=29
Step-by-step explanation:5x5=25
4x5+9=29
inflation means, the same item costs more however is the same item, so if a tomato in January 1st costs $1 and by December 31st it costs $2, the price went up by twice, however is same tomato, it didn't become twice as large, anyhow, inflation eats away value and thus is a Decay case.

(10+×)^2
expand
(10+x)(10+x)
multiply
100+10x+10x+x^2
add
100+20x+x^2
rearrange
x^2+20x+100
if this is what you mean this is the answer if you want to know what x is just set ()=0 and solve
x+10=0
x=-10
but I believe you are asking for the equation hope that helps let me know :)