Question 387027
let x = number of Jones shares Mario purchased
then,x-2 = number of Smith shares Mario purchased
then,2(x-2) = number Adams shares Mario purchased
$45x+$50(x-2)+$30*2(x-2)=$1020
45x+50x-100+60x-120=1020
155x-220=1020
155x=1240
x=8

ans:Mario purchased 8 shares of Jones stock