At a soccer tournament 121212 teams are wearing red shirts, 666 teams are wearing blue shirts, 444 teams are wearing orange shirts, and 222 teams are wearing white shirts.
for every 222 teams at the tournament, there is 111 team wearing shirts.

The answer is:

- For every 2 teams at the tournament, there is 1 team wearing red shirts.

Step-by-step explanation:

As you can see, the total number of shirts in teams is:

When it is mentioned that for every two shirts, one of them is red, it is mentioned that the total of red shirts corresponds to 50%, which can be verified with a rule of three:

Therefore the t-shirts referred to, in effect are the red ones.

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9