Pls help me solve this question using simultaneous equations

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Since it is simultaneous equations, there are 2 equations. The first one is **the relationship between the number of notes of each value** she uses.

Let the number of five-dollar notes Sandra uses be x and the number of ten-dollar notes she uses be y. Since you know that she uses 16 notes altogether:

x + y = 16 — equation 1

Also, you know that the total value is $125. Therefore you can conclude that:

5x + 10y = 125 — equation 2

From equation 1:

x + y = 16

**y = 16 – x**

Substitute this into equation 2:

5x + 10 (16-x) = 125

Expand the brackets:

5x + 160 – 10x = 125

160 – 5x = 125

5x = 35

x = 7

y = 16 – x = 16 – 7 = 9

**Therefore, 7 five-dollar notes are used and 9 ten-dollar notes are used.**

Hope this helps!

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