bantu no 21 dan no 22

gunakan cara eliminasi
22
1/2x + y = 2 1/2 × 4 = 2× + 4y = 10
3x - 4y = -5 = 3x - 4y = -5

5x = 5
x = 1
dan y = 2

maka p + q = 3

21
x + y = 7
x - y = 3

2x = 10
x = 5
y = 2
jadi jawabannya C (5,2)