Tolong Di jawab ya !!! pakai cara,,,besok mau di kumpulin

16. f(x)  = 4x -2
f(a)= 26
4a - 2 = 26
4a = 28
a = 7

17. garis sejajar y = -2/3 x + 6 melalui (4,-5)
misal  garis itu y = - 2/3 x + c
-5 = -2/3 (4) + c
-5 = -8/3 + c
-15 = -8 + 3c
- 7 = 3c
c  = -7/3
garis itu y  = - 2/3 x - 7/3 atau 3y = -2x - 7 atau 3y + 2x = -7

18. P(3, -1) , Q(-4,13), R =(-2, k)
gradien PQ = gradien PR
(y2-y1)/(x2-x1) = (y3-y1)/(x3 - x1)
(13 +1) /(-4-3) = (k +1 )/(-2-3)
14/-7 = (k+1)/(-5)
-2 = (k+1)/ (-5)
k +1 = -2(-5) = 10
k = 9

19.  misal mobil = x , motor = y

banyak kendaraan  ....---> x + y = 90
banyak ban kendaraan--> 4x + 2y = 210  atau 2x + y = 105
.
x + y = 90
2x +y = 105
kurangkan
-x = - 15
x = 15
y = 90-15= 75

biaya = 15(5000)+75(3000) = 75.000 + 225.000 = 300.000