Maths...... :O

Thanx!  heureka....

#1

Mom age = x

Daughter age = y

age difference  = x-y

Now, the Daughter's age MINUS the age difference equals  7

y-(x-y) = 7  or  2y-x=7     (Equation 1)

AND the Mother's age PLUS the age difference is 88

x+(x-y) = 88  or 2x-y =88  ((Equation 2)

From equation 1 :    x = 2y-7    Sustitute into equation 2

                              2(2y-7) - y =88    solve for y =34       = daughter's age     

Equation 1 again  2y-x=7    2(34) - x = 7     x = 61= mom's age

#2  Not sure.....     do you mean that everyone there shakes hands with eveyone else there?

2) In a meeting, everyone shakes hands with another person.

If the total number of shaking hands is 2016 times,

how many people was in the meeting?

Let n = people in the meeting

$\begin{array}{|rcll|} \hline \frac{ n\cdot (n-1) } {2} &=& 2016\ \text{handshakes }\\ n\cdot (n-1) &=& 4032 \\ n^2-n &=& 4032 \\ n^2-n -4032 &=& 0 \\\\ n &=& \frac{1+\sqrt{1-4\cdot(-4032) } }{2} \\ n &=& \frac{1+\sqrt{ 16129 } }{2} \\ n &=& \frac{1+127 } {2} \\ n &=& \frac{ 128 } {2} \\ n &=& 64 \\ \hline \end{array}$

Thanks everyone :)