Angela bought 10 stamps that cost $1 or $1.20. Altogether, her total was $11. How many of each $1 stamps and how many of
each $1.20 stamps did she buy?

Let the first equation be x + y = 10

x = 10 -y

2nd equation will be 1x + 1.2y = 11

Substituting in 2nd equation

(10 - y) + 1.2y = 11

10 - y + 1.2y = 11

.2y = 1

y = 5

If y = 5, x = 5: coz x + y = 10

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