Apawn broker buys a tv set and a computer for $600. he sells the computer at a markup of 30% and the tv at a markup of 20%. if he makes a profit of $165 on the sale of two items, what did he pay for the computer?

Let the cost of the TV be x and that of the computer be y, then
x + y = 600 . . . . . . . (1)
0.2x + 0.3y = 165 . . (2)

From (1), x = 600 - y . . . (3)
Putting (3) into (2) gives:
0.2(600 - y) + 0.3y = 165
120 - 0.2y + 0.3y = 165
0.1y = 165 - 120 = 45
y = 45/0.1 = 450

Therefore, the computer cost him $450.

/-/////////looks tough ‍♂️

Do you need with the x value for the minimum? its always between the two intercepts for a parabola