¹/₃(33x + 15) - ¹/₃(21x + 18) = 10
¹/₃(33x) + ¹/₃(15) - ¹/₃(21x) - ¹/₃(18) = 10
11x + 5 - 7x - 6 = 10
11x - 7x + 5 - 6 = 10
4x - 1 = 10
+ 1 + 1
4x = 11
4 4
x = 3³/₄
If you mean equal payments each week like 30x = 2730 then it would be $91 per week for the 30 weeks to pay it