Step-by-step explanation:
Let,
Cost of one trouser = $x
Cost of one coat = $y
In case 1
x + 3y = 52 (1)
In case 2
4x + 4y = 72
x + y = 18 (2)
On subtracting
x + 3y - (x + y) = 52 - 18
x + 3y - x - y = 52 - 18
2y = 34
y = 34/2
y = $17
From 2
x + y = 18
x + 17 = 18
x = 18 - 17
x = $1
Now,
Cost of 6 trouser and 6 coats
6x + 6y
6(x + y)
6(1 + 17)
6(18)
$108
