3.) John spends $81 on food during his vacation.

That is 45% of the money he brought with him.

How much money does John have left to

spend?

John has 99 dollars after spending on food

Step-by-step explanation:

The total amount John brought with him during his vacation can be expressed as;

Total amount John has=Amount he spends on food+amount he has left after spending on food

where;

Total amount John has=x

Amount he spends on food=45% of x = (45/100) * x=0.45 x

Amount he has left after spending on food = (Total amount he has-amount he spends on food)

Amount he has left after spending on food = (x-0.45 x) = 0.55 x

Equating the amount he spends on food to 0.45 x;

0.45 x=81

x=81/0.45

x=180

Amount he has left after spending on food = (x-0.45 x) = 0.55 x

Replacing the value of x;

Amount he has left after spending on food = (0.55*180) = 99

John has 99 dollars after spending on food