I like your use of the word balance as this is exactly the way you can think of these equations. For example consider your first equation. There are two sides and a balance point (equal sign) between them. The task is to manipulate the quantities on the two sides, all the time maintaining the balance, and conclude with the variable t alone on one side and a number on the other.
The first task is to interpret 75%. the term "percent" means per one-hundred so 75% is the fraction 75/100. Hence the first equation can be written
75/100 t = 18
or in decimal form
0.75 t = 18.
To manipulate the equation, maintain the balance and leave t alone on the left side you can divide both sides by 0.75. Thus
0.75 t/0.75 = 18/0.75
t = 24.