Create a graph that shows taxes paid as a function of total income for the total income between $$0$ and $$60,000.$

How many different slopes are on this graph?

$$ For taxable income from $$0$ to $$15,000,$ you pay $10\%$ of your taxable income in taxes, plus

$$ For taxable income above $$15,000,$ you pay $18\%$ of your taxable income.