Answer:
The sales mix ratio is 3:1:2
E F G
Selling Price 28 20 59
Multiply Sales Mix Ratio 3 1 2
Weighted selling price 84 20 118
The sales price per composite unit can be calculated by adding up weighted selling prices which is 84+20+118=$222 per composite unit.
I have assumed that the selling prices of product E, F and G are 28, 20 and 59 respectively.