Justine W. answered 02/24/22
The Dancing Physicist
First, I recommend assigning a letter to both types of tickets:
s = senior citizen
c = child
Now we know both of the variables we're looking for :D
Next, make each separate statement into an equation:
3 senior citizen tickets (3s) and 9 children tickets (9c) sold for a total of $75 would be 3s+9c=75
8 senior citizen tickets (8s) and 5 children tickets (5c) sold for a total of $67 would be 8s+5c=67
Now with a little rearranging and substituting we can easily solve for the cost of a single ticket for both senior citizens and children!
The first equation:
3s+9c=75
~subtract 9c from both sides to isolate the s variable~
3s=75-9c
~divide by 3 to get the s variable completely alone~
s=25-3c
Then substitute this cool equation into the s variable in the second equation!
8s+5c=67
8(25-3c)+5c=67
~multiply it out~
200-24c+5c=67
~now solve for c woohoo~
200-19c=67
19c+67=200
19c=133
c=7
So, now we know that a children's ticket costs $7. Finally, we can plug this back into the first simplified equation and find the cost of a senior citizen's ticket!
s=25-3c
s=25-3(7)
s=25-21
s=4
There we go! A senior citizen's ticket costs $4. This method can be applied to various word problems in your future studies <3