Luis and Berto sell TVs. Last month Berto sold 15 more TVs than Luis. Together they sold 163. How many TVs did Luis sell?

solution - Breto sell - X

Luis Sell - Y

then  X +15 = Y   => Y - X = 15 ......................(1)

 X + Y = 163   => Y + X  = 163 ........................(2)

By solving these two eq.

(1)  +(2)  WE GET

2Y = 178

Hence Y = 178/2 = 89  ANSWER