tertre

Yes, it is rational; 31.662, and it goes on.

Yes, it is a rational number; decimal.

That is wrong; 3*2+3=9, not 22

This is just combinations, 15C2- \(\frac{15!}{2!*13!}=\frac{15*14}{2*1}=15*7=\boxed{105}\)

Gavin is correct! You have to put the brackets around 1/3, not just 1. So, \((\frac{1}{3})^4=\frac{1}{81}\)

Here to solve questions,

Here's a similar problem to think of:

One elephant can eat 2000 pounds of grass in 20 days.

He and his friend can eat it in 10 days.

How long does it take for the elephant's friend to eat alone?

Solution:

Again, elephant 1:1/20

elephant + friend: 1/10

Equation: 1/20+x=1/10

Take 1/20 to the other side, to get: 1/10-1/20=2/20-1/20=1/20 days

So, his friend can eat the grass alone in \(\boxed{20}\) days.

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Here's a different type of problem to think of.

A person can finish a poster completely in 20 minutes. His friend can finish the same poster in 10 minutes. How many minutes will it take if they work together:

1/20+1/10=1/20+2/20=3/20

1(whole)/3/20=20/3=\(6 \frac{2}{3}\)minutes.

Supplementary: 180

(180-x)*4-120

x=720-4x-120

5x=120

180-120=\(\boxed{60^\circ}\) degrees.

We can set up an equation, here:

First number= \(x\)

Second number=\(2x+3\)

So,  \(x+2x+3=66\)

Simplifying more, we have:

\(3x+3=66\)

\(3x=63\)

\(x=21\)

Since it's asking for the larger number, we simply do:

\(21*2+3=\boxed{45}\)

Also, FiestyGeco, a user posts multiple questions in 1 thread and just reads the user's answers, not solutions.