Question 63261
LEt the coffee merchant has x lb and y lb of the coffee beans

x + y =100

x*  9 +y * 12 = 11.25 * 100



We shallsolve the given equations

WE rewrite the equation(1) as

x = 100 - y -->(3)

Now substitue equation(3) in equation(2), we get

(100 - y) * 9 + y *12 = 11.25 * 100

900 - 9y + 12y = 1125

900 + 3y = 1125

3y = 1125 - 900 = 225

3y =225

Divide by 3 we get,

y = 225 / 3

y = 75 lb


Now substitue the "y" value in equation)3), we get

x = 100 - 75  =  25lb

Therefore the quantity  of coffee beans of first type is 75lb and the second type is 25 lb