Answer:
Proportion states that the two fractions or ratios are equal
As per the statement: Mrs. Hwang is taking her vehicle to the shop to have the gas tank expanded by 10 gallons. Now, it costs her $42.56 to fill the tank. Once the new tank is in, it will cost her $72.96
Let the tank size now be x
Since, the gas tank expanded by 10 gallons = x + 10
by definition of proportion ;

by cross multiply we get;

using distributive property;


Subtract 42.56x from both sides we get;

Divide both sides by 30.4 we get;
x = 14
Therefore, the tank is her now is, 14 gallons