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

a negative exponent is translated as follows:

so, we have

really really sorry if i'm

-12 -5(x + 4) = 3x

-12 - 5x - 20 = 3x

-12 - 20 - 5x = 3x

-32 - 5x = 3x

    + 5x   + 5x

-32 = 8x

8         8

- 4= x