Last Month Sellers Of Good Y Took In 100 And Sold 50 Units Of Good Y This Month Sell 1189751

Last month, sellers of good Y took in $100 and sold 50 units ofGood Y. This month sellers of Good Y raised their price, took in$120 and sold 40 units of Good Y. At the same time, the price ofGood X statyed the same, but sales of Good X increased from 20units to 40 units. We can conclude that Goods X and Y are

Answer:substitutes, and have a cross-price elasticity of 1.67

please explain how to get 1.67? and show the work process

Thank you.