no 1 dan 2. karena nggak paham, jdi tolonf bantuan

7x-2y=10 |×5| no 1
2x+5y=14|×2|
------------------- +
35x-10y=50
4x+10y=28
-------------------- +
39y=78
y=78:39
y=2

2x+5y=14
2(2) +5y =14
4+5y=14
5y=14-4
5y=10
y=10: 5
y=2

8(2) -3(2) =16-6=10
jawabannya D. 10

8x+3y==25.200 |×1|
2x+5y=14.800 |×4|
------------------------------ -
8x+3y=25.200
8x+20y=59.200
-------------------------- -
-17y=-34.000
y=-34.000: -17
y=2.000

2x+5y=14.800
2x+5(2.000) =14.800
2x+10.000=14.800
2x=14.800 - 10.000
2x=4.800
x=4.800: 2
x=2.400

5x+4y= 5(2.400) +4(2.000) =12.000+8.000=20.000
jawabannya c