Answer:
13. Let's say Jason's age is x, Omar's age is y and Henry's age is z. Then we have:y = 3x (Omar is three times as old as Jason) z = x + 5 (Henry is five years older than Jason) x + y + z = 80 (Their total age is 80) Now replace y and z in the last equation with the two other equations and you get: x + 3x + (x + 5)= 80 Calculate brackets: x + 3x + x + 5 = 80 Move 5 over and add up the x: 5x = 75 x = 75/5 = 15 So Jason is 15. Now we put x = 15 into the other equations and we get: Omar's age: y = 3*15 = 45 Henry's age: z = 15 + 5 = 20 So Omar is 25 years older than Henry.
14.
Let c = chickens and d = ducks, then:
c = 2d
c - 272 = 1/2 (d - 16)
We can rewrite the expression in terms of one variable, d:
2d - 272 = 1/2 (d - 16)
2d - 272 = 1/2d - 8
3/2d = 264
d = 176
c = 2 * 176 = 352
She had 352 chickens in the beginning.
15.
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