Equation formation.
Let the cost of pants be 'p' and that of shirts be 's'
3 p + 3 s = 286..........equation(i)
3 p = 2× 3 s
3 p = 6 s
p = 2 s...........equation(ii)
Equation solving
3 (2 s) + 3 s = 286
9 s = 286
s = 31.78
Cost of pants
p = 2s
p = 2× 31.78
p = 63.56
Answer = $63.56