
Alex G. answered 03/02/21
Purdue Engineer, Math Tutor for High School and Middle School
Hi Tanner, we'll start by setting up our system of equations, with x and y representing the number of each envelope. The setup would be as follows:
x + y = 150
0.44x + 0.61y = 74.5
Using substitution, isolate y and solve for x:
y = 150 - x
0.44x + 0.61(150 - x) = 74.5
0.44x + 91.5 - 0.61x = 74.5
-0.17x = -17
x = 100
Solve for y:
y = 150 - 100
y = 50
So 100 were sent at 44 cents while 50 were sent at 61 cents.
Hope that helps!