Answer:
B. 6.5
Step-by-step explanation:
You can use the 5 against the unknown number and add a few more moves which makes it 6.5.. It's easier in my head man.
Let
x-----------> the number of kids
y----------> the number of adults
we know that
2.5x+6y=$7150---------> equation 1
x=2y-------------> equation 2
substitute 2 in 1
2.5*[2y]+6y=7150-----> 5y+6y=7150----> 11y=7150-----> y=650
x=2y----> x=2*650----> 1300
the answer is
the number of kids is 1300