this ones hard, i think. i cant find a patten. I asked my step dad whos a wiz at maths and he cant get it either. So anyone who can help please do. Thanks

if 5 * 3 = 4
2 * 8 = 2
6 * 3 = 3
find the value of

1 * 7

One more thing a patten i cant get -

2 1/2, 5 , 10 , 20 _ _

Thanx for all your help Dan it was awesome!! Saved me thank -you heapss xo

2. Originally Posted by emm
One more thing a patten i cant get -

2 1/2, 5 , 10 , 20 _ _
Its just doubling every previous number. So the next number is 40

3. Hello, emm!

I don't understand the first one either.
A few more examples would have helped immensely . . .

Given: . $\begin{array}{cccc}
{\color{blue}[1]} &5 \star3 &=& 4 \\
{\color{blue}[2]} & 2 \star 8 &=& 2 \\
{\color{blue}[3]} &6 \star 3 &=& 3 \end{array}$

Find the value of: . ${\color{blue}[4]}\;\;1 \star 7$

In [1] and [3], we have: . $a \star b\;\text{ where } a > b$

. . The rule appears to be: . $a \star b \;=\;\frac{a+b}{a-b}$

In [2] and [4], the rule is unclear.

Could it be this simple?. . If $a < b\!:\;\;a\star b \:=\:a$