Question 990533
.
F=number of 5c stamps; T=number of 20c stamps
.
F+T=25
T=25-F
.
5F+20T=440
5F+20(25-F)=440
5F+500-20F=440
-15F=-60
F=4
ANSWER: He bought four 5c stamps.
.
T=25-F=25-4=21
ANSWER 2: He bought twenty one 20c stamps.
.
CHECK:
.
5F+20T=440
5(4)+20(21)=440
20+420=440
440=440