Aldo's Coffee Shop makes a blend that is a mixture of two types of coffee. Type A coffee costs Aldo $\$ 4.20$ per pound, and type B coffee costs $\$ 5.80$ per pound. This month, Aldo made 158 pounds of the blend, for a total cost of $\$ 762.80$. How many pounds of type A coffee did he use? Number of pounds of type A coffee:

Step 1 ：Let's denote the amount of type A coffee as 'a' and the amount of type B coffee as 'b'.

Step 2 ：We know that the total amount of coffee is 158 pounds, so we can write this as an equation: \(a + b = 158\).

Step 3 ：We also know that the total cost of the coffee is $762.80. We can express this as another equation: \(4.2a + 5.8b = 762.80\).

Step 4 ：We can solve this system of equations to find the values of 'a' and 'b'.

Step 5 ：The solution to the system of equations is \(a = 96\) and \(b = 62\).

Step 6 ：So, Aldo used \(\boxed{96}\) pounds of type A coffee.