7. YZ
8. 27,49
9. 51
10.c
11. b
Answer: 11 and 24
Step-by-step explanation:
Given
There are 35- 50 cents and 20 cents coins
The total of them is 10.3 euros
Suppose no of 50 cents coins is x and 20 cents is y
so we can write

Also,

Solving (i) and (ii) we get

There are 11 fifty cent and 24 twenty cents coins
7000+(600•12)=14200
Linear
Add 5 on both sides and it will give you ×=-10
Just add the equations and the y-terms will cancel.
-4x + 4y = -16
8x - 4y = 24
SUM
4x = 8
x = 2
plug into one of the equations and solve
-4(2) + 4y = -16
-8 + 4y = -16
4y = -8
y = -2
Answer (2, -2)