A percent is a proportion of something that can come from a variety of different numbers depending on what you are measuring. 14.5% is not the same as 14.5 because the 14.5% isn’t necessarily 14.5 of a certain amount. For example, $14.50 of the $100 you have could be from your grandparents; making 14.5% of your money from your grandparents but a deposit of $145 into a bank account that already has $855 would mean that 14.5% of the money in that bank account was from that deposit but $145 does not equal $14.50. They just have the same proportion just different on different scales.
Hope this is what you were looking for.
The picture in the attached figure
we know that
surface area=2*area of the base+perimeter*height
area of the base=area of the triangle
area of the base=3*4/2----> 6 cm²
perimeter of the base=perimeter of triangle
perimeter=3+4+5----> 12 cm
height=x cm
surface area=2*6+12*x
surface area=204 cm²
12+12*x=204
12*x=204-12
12*x=192
x=192/12
x=16 cm
the answer is16 cm