The available balance online may not reflect all debit transactions or all checks that were written. Some recent debit transactions and check written may not have been posted to his account yet. The available balance would need to subtract any outstanding debit transactions and any written checks that have not cleared his account. This would yield the correct available balance.
A + c = 824 represents number of tickets to sell
20a + 12c = 13,344 represents cost of each type of ticket
multiply equation 1 by -12 to cancel the variable 'c' and solve for 'a'
-12(a + c = 824)
-12a - 12c = - 9888
20a + 12c = 13,344 add equations together
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8a = 3456 divide both sides by 8
a = 432
To find children's tickets substitute adult numbers back into equation 1.
a + c = 824
432 + c = 824
subtract 432 from both sides
c = 392
adult 432, children 392
Y-y
——-
X-x
21-9=12
5-(-1) =6
So the answer is D
Right angle because that has 90 degree angle