15+21= in distributive property to factor out the greatest common factor

Mathematics

1 answer:

ASHA 777 [7]3 years ago

5 0

Answer:

So the greatest common factor 15 and 21 is 3.

Step-by-step explanation:

You might be interested in

Use the principle of inclusion and exclusion to find the number of positive integers less than 1,000,000 that are not divisable

wel

This is a simple problem based on combinatorics which can be easily tackled by using inclusion-exclusion principle.
We are asked to find number of positive integers less than 1,000,000 that are not divisible by 6 or 4.
let n be the number of positive integers.
∴ 1≤n≤999,999
Let c₁ be the set of numbers divisible by 6 and c₂ be the set of numbers divisible by 4.
Let N(c₁) be the number of elements in set c₁ and N(c₂) be the number of elements in set c₂.

∴N(c₁) = $\frac{999,999}{6} = 166666$
N(c₂) = $\frac{999,999}{4} = 250000$
∴N(c₁c₂) = $\frac{999,999}{24} = 41667$
∴ Number of positive integers that are not divisible by 4 or 6,

N(c₁`c₂`) = 999,999 - (166666+250000) + 41667 = 625000
Therefore, 625000 integers are not divisible by 6 or 4

8 0

3 years ago

When servicing a heating boiler and radiators, a plumer knows that the time he will take is given by the formula

Allushta [10]

Answer:

£110

Step-by-step explanation:

We know how much time it takes for a boiler and a radiator, and we need to know how much it will cost for 1 boiler and 4 radiators. We have an initial cost of £30, and since hes doing a boiler - which we know takes an hour - we can already add £20 for a start of £50.

Now, there are 4 radiators, that take 45 minutes each. We need to use this equation:

$(45*4)/60$

We divide by 60 because there are 60 minutes in an hour, and he charges by hour. So:

$180/60=3$

Now, to find out how much to charge, we need to figure out how much to add to the £50. Since it's £20 an hour, and it takes 3 hours to do the 4 radiators, we need to multiply:

$3*20=60$