(b) Let the number of people who used Samsung, Nokia and Motorola phones = x
∴ Number of people who used only Motorola = (x + 1 0 ) Now, number of people who used only Motorola and Samsung = 50 - (x + 10)- 34 = 6 - x ∴ Number of people who used Motorola and Samsung = ( 6 - x) + x = 6 Thus, the number of people did not use Motorola, but used Nokia and Samsung = 2 x 6 = 12