Answer:
20
Step-by-step explanation:
32/1 / 8/5= 32/1 x 5/8= 160/8=20
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Answer: 5 km walking and 30 km by bus
Step-by-step explanation:
Yochanan walked from home to the bus stop at an average speed of 5 km / h. He immediately got on his school bus and traveled at an average speed of 60 km / h until he got to school. The total distance from his home to school is 35 km, and the entire trip took 1.5 hours. How many km did Yochanan cover by walking and how many did he cover by travelling on the bus?
walking - 5km/h bus - 60km/h
distance walking - d₁ distance bus - d₂
time walking - t₁ time bus - t₂
d₁ + d₂ = 35
t₁ + t₂ = 1.5
v = d/t
vwalking = d₁/t₁
5 = d₁/t₁ ⇒ d₁ = 5t₁
vbus = d₂/t₂
60 = d₂/t₂ ⇒ d₂ = 60t₂
d₁ + d₂ = 35 ⇒ 5t₁ + 60t₂ = 35
_________________________
5t₁ + 60t₂ = 35
t₁ + t₂ = 1.5 (*-5)
5t₁ + 60t₂ = 35
-5t₁ -5t₂ = -7.5 (+)
__________________________
55t₂ = 27.5
t₂ = 27.5/55 = 0.5 h
t₁ + t₂ = 1.5 ⇒ t₁ = 1.5 - 0.5 = 1h
d₁ = 5t₁ ⇒ d₁ = 5.1 = 5 km
d₂ = 60t₂ ⇒ d₂ = 30.0.5 = 30 km
Answer:
y = -2 ( (x^2) + (2*x*5) + (5^2)) - 30
y = -2 ( x^2 + 10x + 25) - 30
y = -2x^2 - 20x - (2*25) - 30
y = -2x^2 - 20x - 50 - 30
y = -2x^2 - 20x - 80
I suspect you meant
"How many numbers between 1 and 100 (inclusive) are divisible by 10 or 7?"
• Count the multiples of 10:
⌊100/10⌋ = ⌊10⌋ = 10
• Count the multiples of 7:
⌊100/7⌋ ≈ ⌊14.2857⌋ = 14
• Count the multiples of the LCM of 7 and 10. These numbers are coprime, so LCM(7, 10) = 7•10 = 70, and
⌊100/70⌋ ≈ ⌊1.42857⌋ = 1
(where ⌊<em>x</em>⌋ denotes the "floor" of <em>x</em>, meaning the largest integer that is smaller than <em>x</em>)
Then using the inclusion/exclusion principle, there are
10 + 14 - 1 = 23
numbers in the range 1-100 that are divisible by 10 or 7. In other words, add up the multiples of both 10 and 7, then subtract the common multiples, which are multiples of the LCM.
