Answer:
40
Step-by-step explanation:
Let's call blueberries, raspberries, grapes and cherries b, r, g, and c respectively. We can write:
b + r + g + c = 280 (1)
r = 2b (2)
g = 3c (3)
c = 4r (4)
We can plug (2) into (1) to get b + 2b + g + c = 280. Then, we can re-write (4) into r = c / 4 and plug that into (2) which gets us c / 4 = 2b, and when we re-write that we get c = 8b (5). Let's plug that into (1) to get b + 2b + g + 8b = 280. Next, we'll re-write (3) to get g / 3 = c, and we can plug that into (5) to get g / 3 = 8b so then g = 24b and plug that into (1) to get b + 2b + 24b + 8b = 280 → 35b = 280 → b = 8. We can plug this into (5) to get c = 8 * 5 = 40. Hope this helps!