1. A.
x parrot fish + y triggerfish = 320 total fish.
y = 7x shows that there are 7 times as many triggerfish.
2. C
x + y shows a total score of 425.
y = 2x - 70 shows that Michael's score, y, is 70 less (minus) than twice Kathryn's
3. write two equations
x + y = 27 total feet
2x + 3 = y
Substitute 2x + 3 for y in the first equation
x + (2x + 3) = 27
3x + 3 = 27
3x = 24
x = 8
Substitute 8 in to either equation to find the other length.
8 + y = 27
y = 19
The shorter piece is 8 and the longer piece is 19
4. x + y = 3200 people -> y = 3200-x
8x + 12y = 33,040 dollars
8x + 12(3200 - x) = 33040
8x + 38400 - 12x = 33040
-4x = -5360
x = 1340 (1340 children)
1340 + y = 3200
y = 1860 adults
5. I don't think the numbers for this were put in correctly because I get a decimal and a negative number when I solve for it but hopefully if you do get the correct cost/amount of coins you will understand this well enough to do it on your own. Hope I helped!