There were 420 T-shirts at a stall. ³₇ of them were without collars. T-shirts without collars were priced at $11 each. T-shirts with collars were priced at $7 each. The stall owner sold ¹₅ of the T-shirts without collars and ³₅ of the T-shirts with collars. How much did he collect from all the T-shirts he sold?
Number of T-shirts = 7 u

7 u = 420

1 u = 420 ÷ 7 = 60

Number of T-shirts without collars
= 3 u
= 3 x 60
= 180

Number of T-shirts without collars sold 
= ¹₅ x 180
= 36

Number of T-shirts with collars
= 4 u
= 4 x 60
= 240

Number of T-shirts with collars sold
= ³₅ x 240
= 144

Amount that the stall owner collected from the sale of the T-shirts without collars
= 36 x 11
= $396

Amount that the stall owner collected from the sale of the T-shirts with collars
= 144 x 7
= $1008

Total amount that the stall owner collected from all the T-shirts he sold
= 396 + 1008
= $1404

Answer(s): $1404