the expression of the income is,
y = 16x - 130
the expression for cost or manufacturing cost is,
y = 8x + 150
for break-even order
it means no profit or no losss
so the total cost of wallets will equal to total income,
16x - 130 = 8x + 150
16x - 8x = 150 + 130
8x = 280
x = 280/8
x = 35
so the number of wallets order is 35 for break-even.