Problema Solution
An office has some 20-cent stamps and some 28-cent stamps. Altogether the office has 140 stamps for a total value of $31.20. How many of each type of stamp does the office have?
Answer provided by our tutors
let
x = the number of 20-cent stamps
y = the number of 28-cent stamps
altogether the office has 140 stamps
x + y = 140
for a total value of $31.20 = 3120 cents
20x + 28y = 3120 divide both sides by 4
5x + 7y = 780
by solving the system of equations
x + y = 140
5x + 7y = 780
we find
x = 100 20-cent stamps
y = 40 28-cent stamps
click here to see the step by step solution of the system of equations
the office has 100 20-cent stamps and 40 28-cent stamps.